Computer_Basics from Hawassa Univer.pptx

Computer basics by HU

1. Hawassa University Digital Literacy Training Topic on Computer Basics August, 2019

2. 1. Introduction 1.1 Definition A computer is an electronic device that: Accepts data and instructions (INPUT) Processes the data according to the instructions (PROCESS) Stores the data and the results of processing (information) (STORAGE) Displays the information (OUTPUT) 2

3. 1.2 Application Areas of Computers Computers are applied in almost all areas, including: Business – E.g. payroll calculations, sales analysis, financial forecasting, managing employees database, etc.) Banking – E.g. like online accounting facility, ATM machines, etc) Insurance - to maintain a database of all clients with information showing procedure to continue with policies, starting date of the policies, next due installment of a policy, maturity date, interests due, survival benefits, bonus, etc. Education – E.g. Computer Based Education, which involves control, delivery, and evaluation of learning; assisting in searching information. Marketing – E.g. advertising, home shopping, etc. Health Care – E.g. diagnostic system, patient-monitoring system, pharma information system, surgery, etc. 3

4. Application Areas of Computers (Cont’d) Engineering Design – Examples include: Structural Engineering - stress and strain analysis for design of ships, buildings, bridges, airplanes, etc. Industrial Engineering - design, implementation and improvement of integrated systems of people, materials and equipments. Architectural Engineering - planning towns, designing buildings, determining a range of buildings on a site using both 2D and 3D drawings. Military – e.g. missile control, military communication, military operation and planning, smart weapons, etc. Communication – E.g. E-mail, Chatting, FTP, Telnet, Video-conferencing, etc. Government - E.g. Budgets, Sales tax, Income tax, Male/Female ratio, Computerization of voters lists, Computerization of driving licensing system, Computerization of PAN card, Weather forecasting, etc. + 4

5. 1.3 Types of Computers 5

6. 1.3 Types of Computers… cont’d 6 Computers are classified based on different criteria: Based on their purposes: General-purpose – used for a variety of tasks/purposes For example, the personal computers (PCs) currently in wide use are general-purpose computers. E.g. the PCs in wide use in our labs and Internet cafés, Special-purpose – are specially designed to perform one specific tasks . E.g a computer that guides a missile , Public telephone box,

7. Types of Computers (cont’d) Based on the method of data they handle computers can be classified as analog, digital and Hybrid: Analog computers: process analog/ continuous data. Continuous data refers to those values that can not be discrete . Example: - Temperature, air pressure, speed, current etc. Analog computer calculates the result by measuring the continuous change in these quantities. They do not require any storage capability because they measure and compare quantities in a single operation. Example : - Voltmeter, Speedometer By analog, we mean continuously varying quantity. Digital computers : process digital data which is discrete .Digital data assume one of two values, 1 (high) or 0 (low). The natural language of digital computer is therefore called binary language (Machine Language. They are more precise and accurate than analog computers . Hybrid computers : Are computers that exhibit features of both analog and digital computers. 7

8. Types of Computers (cont’d) Based on the size or function Super computers Most powerful and expensive They are the fastest, most expensive and most powerful computers available today Used for problems requiring complex operations (e.g. tracking spaceship, weather forecasting ) Mainframe computers they can serve hundreds or thousands of users, handling massive amounts of input, output and storage. Capable of great processing speed and data storage Not as powerful as supercomputers Housed in special rooms with special power and environmental control. They are used as e-commerce servers handling transactions over the Internet and allowing its users to maintain a large information storage at centralized locations, 8

9. Types of Computers (cont’d) Minicomputers( Midrange computers) : A mini computer is a small digital computer, which normally is able to process and store less data than a mainframe but more than a microcomputer. Generally Minis perform many of the tasks that a mainframe can, but on a reduced scale. They are Often connected to a mainframe in order to perform auxiliary operations. They are multi-user computers designed to meet the computing needs for several people simultaneously in a small to medium size business environment. Microcomputers: It is a small, low cost digital computer, which usually consists of a microprocessor, a storage unit, an input channel and an output channel . They are the least powerful and most popular and widely used single user computers Four types Desktop ( which is not Portable ) Notebook or laptop Tablet PC Handheld devices such as PDA Smartphone 9

10. 2. The Computer System A complete computer system includes four distinct parts: Hardware, Software, Data and Users. Data – raw facts to be processed by computer. Includes numbers, text, images, audio or video All data are represented as strings of bits. Data is processed to produce information. Users – people operating the computers. 2.1. Computer System Components 10

11. Computer System Components (cont’d) Hardware – Physical components that you can touch or feel. It consists of: The system unit which houses the motherboard, microprocessor, power supply, memory, etc. The keyboard, monitor, and mouth. Other peripheral devices like printer, digital camera, scanner, LCD projector, etc. 11

12. Computer System Components (cont’d) Software or program is a set of detailed instructions that tell the computer what to do. A software may come in different media, but at the time of running, it is loaded onto memory. A processor fetches an instruction from memory, decodes it and then executes the required operation. When an instruction has been executed the next instruction is fetched, decoded and executed, etc. 12

13. 2.2 Computer Hardware 2.2.1 A physical setup of a computer System Unit Mouse Keyboard Monitor CD-ROM Drive Floppy Disk Drive 13

14. Computer Hardware (Cont’d) System unit houses the major components of the computer. 14

15. Computer Hardware (Cont’d) 15

16. Computer Hardware (Cont’d) Motherboard CPU (Central Processing Unit) 16

17. Computer Hardware (Cont’d) SIMM (Single Inline Memory Module ) HDD (Hard Disk Drive) Power Supply 17

18. Computer Hardware (Cont’d) Power supply converts mains AC to low-voltage regulated DC power for the internal components of a computer . Expansion cards – small circuit boards used to add a new ability to a computer. E.g. video cards, modems, network cards, sound cards, etc. Expansion slots – a socket on the motherboard where expansion cards can be plugged into. There exist different types of slots & cards; an expansion card fits into similar type of slot. 18

19. Computer Hardware (Cont’d) Types of Expansion Slots 19

20. Types of Expansion Slots PCI (Peripheral Component Interconnect) most commonly found and used bus in PCs during the late 1990's and early 2000's allows devices to be inserted quickly and easily (PnP). AGP (Accelerated Graphics Port) specifically designed to deal with graphics adapters Older PCs used AGP; newer ones use PCI express. 20

21. Types of Expansion Slots (Cont’d) PCI Express (or PCIe ) The best type of expansion slot to have in your PC It is by far the fastest and most efficient slot. PCI Express in all its flavors: 1x, 2x, 4x, 8x, 16x and 32x has much greater bandwidth than basic PCI. For example: PCI has a speed of 132 MB/s PCIe 1x has a speed of 250[500] MB/s PCIe 16x has a speed of 4000[8000] MB/s 21

22. Computer Ports Computer Port is an interface between the computer and other computers or peripheral devices. 22

23. 2.2.2 Operational Setup of a Computer 23

24. Operational Setup of a Computer (cont’d) Processor or Central Processing Unit (CPU) The computing part of the computer It is referred to as the brain of the computer It has three main parts: Arithmetic and Logic Unit (ALU) – actual arithmetic and logical operations The Control Unit (CU) – directs the operations of the entire system. Fetch, decode and execute, central nervous system. Registers – special purpose, high speed temporary memory units. hold data, instructions, addresses and intermediate results. E.g. Program Counter, Instruction Register, Accumulator, Memory Address Register, Memory Buffer Register and Data Register 24

25. Operational Setup of a Computer (cont’d) Input Unit – consists of such devices that are used to enter data and instructions into the computer. Examples include, keyboard, mouse, joystick, light pen, track ball, scanner, graphic tablet, optical character reader, bar code reader, etc. Keyboard The standard input device. Looks like the traditional typewriter, with some additional keys for performing additional functions. Of two sizes 84 keys or 101/102 keys, but now keyboards with 104 keys or 108 keys are also available. 25

26. Input Unit (Cont’d) The keys in a keyboard consist of: Keys Description Typing Keys Include the letter keys (A-Z) and digit keys (0-9) which generally give same layout as that of typewriters. Numeric keypad Found at the right side of the keyboard and are used for entering numbers and moving the pointer. Function keys Twelve function keys, F1 – F12, at the first row of the keyboard; th ey may be programmed to perform different tasks. Modifier keys include keys like Alt, Ctrl , Shift, Caps Lock, Num Lock, Space bar, Tab, and Print Screen. Cursor Movement Keys Found between the alphanumeric keys and numeric keypad, they are used to move the cursor. 26

27. Input Unit (Cont’d) The mouse Most popular pointing device. Used to control the position of cursor on screen. A ball at its base senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed. It has two buttons called left and right button and a wheel is present between the buttons. Faster than the keyboard to move the cursor 27

28. Input Unit (Cont’d) Joystick a pointing device used to move cursor position on a monitor screen. mainly used in Computer Aided Designing (CAD) and playing computer games. Light Pen a pointing device similar to a pen. used to select a displayed menu item or draw pictures on the monitor screen. 28

29. Input Unit (Cont’d) Track ball mostly used in notebook or laptop computer, instead of a mouse. pointer can be moved by moving fingers on the ball. Touch pad found in most portable computers. operated by using your finger and dragging it across a flat surface 29

30. Input Unit (Cont’d) Scanner works more like a photocopy machine. captures images from the source which are then converted into the digital form. Digitizer also known as Tablet or Graphics Tablet, it converts analog information into digital form. E.g. a signal from the television or camera. 30

31. Input Unit (Cont’d) Microphone to input sound that is then stored in digital form. Optical Character Reader (OCR) used to read a printed text, convert it into a machine readable code and stores the text on the system memory. Bar code reader scans a bar code image, converts it into an alphanumeric value which is then fed to the computer. 31

32. Output Unit Output devices – peripheral devices through which processed data is made available for humans. Convert machine readable information into human readable form. Output from such devices takes one of two forms: Softcopy E.g. monitor display, audio output, projector display Hardcopy E.g. printed material using printers, plotters or microfilms 32

33. Output Unit (Cont’d) Monitor Also called visual display unit VDU), it displays the information produced by the video card. Based on the color they produce, they can be categorized into three types. Monochrome - one color text/image on single color background, i.e. white on blue, or green on black. Grayscale – shades of gray on a white background. Color – can display different colors, from 16 to more than 16 million colors. 33

34. Based on the technology used to make computer monitors, they can be broadly categorized into three types . CRT (Cathode Ray Tube) LCD (Liquid Crystal Display) LED (Light-Emitting Diodes) Output Unit (Cont’d) 34

35. CRT (Cathode Ray Tube) Monitors Electrons are fired at phosphor dots on the screen. The dots are grouped into picture elements called pixels, which glow when struck by electrons. In color CRT monitors, each pixel contains a red, green and blue dot. These glow at varying intensities to produce color images. They are highly reliable and efficient, capable of generating a resolution of up to 2048 x 1536 pixels, thereby providing a clear picture quality. Output Unit (Cont’d) 35

36. LCD (Liquid Crystal Display) Monitors Made of two layers of a polarizing material with a liquid crystal solution in between. An electrical signal makes the crystals line up in a way as to regulate the light going through. All crystals lined up means no light gets through and hence black screen A color LCD screen uses groups of 3 color cells. They are compact and lightweight. They consume less electrical power than CRT. There are two types of LCD technology available: The active matrix (TFT) and a passive matrix. TFT technology is more secure and reliable, and generates better picture quality. Output Unit (Cont’d) 36

37. Important monitor specifications include: Size the diagonal measurement of its face in inches. 17” – 22” monitors are common. Resolution number of pixels on the screen. Common resolutions include: VGA (Video Graphics Array):640 x 480 pixels SVGA (Super VGA): 800 x 600 pixels XGA (extended VGA): 1024 x 768 pixels SXGA: 1280 x 1024 pixels Refresh rate Shows how often the picture is redrawn on the monitor. With low rate, picture will flicker. So, high refresh rate is desirable. 60 times per second is tolerable at low resolutions for most people. 75 times per second or more is better and is necessary for high resolutions.  Output Unit (Cont’d) 37

38. Aspect Ratio Ratio of horizontal pixels to vertical pixels; typical values are 16:10 or 16:9 Contrast ratio Difference in brightness from the brightest to the darkest; typical contrast ratio is 1000:1 Dot (pixel) pitch Space between the pixels (or dots) that make up the images on your computer monitor. The smaller the pixel pitch, the better the image quality will be on your screen. Output Unit (Cont’d) 38

39. Video Adapter Cards convert information from the CPU into a format used by the monitor. can be built into the motherboard but, in most cases, it is installed as an expansion card. video adapter card specs are similar to those of the monitor video adapter cards come their own memory, separate from the computer’s main memory. Amount of video memory determines the maximum number of colors that can be displayed at a given resolution. Output Unit (Cont’d) 39

40. Storage Unit Storage unit comprises of two types: primary and Secondary Primary – fast but limited; it consists of: RAM (Random Access Memory) stores data and programs needed by processor Temporary and volatile Made from semiconductors ROM (read Only Memory) Permanent and non-volatile contains minimum instructions that the computer needs to get started 40

41. Secondary – bulk but slow. It is not directly accessible by processor Permanent storage Examples include: Floppy disks Hard disks Magnetic tape Compact disks DVDs Flash disks Storage Unit (Cont’d) 41

42. Hard disk drive (HDD) Internal or external Rigid rotating disks (platters), stacked on a spindle. Platters rotate at high speed, Read/Write heads move back and forth recording/ reading magnetic information on both sides of the platters. Hard disk has to be formatted before use. Formatting creates these areas: Boot sector File Allocation Table (FAT) Root Folder Data Area Storage Unit (Cont’d) 42

43. Floppy disk Slower and lower capacity than HDD Thin, flexible disk inside a protective plastic cover. Removable media Write-protect window Mainly used to carry private data/info from place to place Now, it is obsolete Storage Unit (Cont’d) Write-protect Window 3 ½”, 1.44MB Diskette 43

44. Magnetic Tape Used to backup files from HDD Very slow, but low cost Tapes need to be formatted before use Backup files are not directly read from tap; they need to be restored to HDD CD-ROM (Compact Disc Read Only Memory) Can only read to CD-ROM Use optical technology First CD-ROMs (1X) transferred at the rate of 150MB/s 2X CD-ROMS can transfer at the rate of 300MB/s, etc. They have storage capacity of about 650MB Storage Unit (Cont’d) 44

45. CD-R (CD-Recordable) allows to write to and read from a Compact Disc, but not erase or change what you record. CD-RW (CD-Read/Write) Rewritable CD DVD (Digital Video/Versatile Disc) Higher storage capacities than other CDs Can store up to 17GB Storage Unit (Cont’d) 45

46. 2.3 Computer Performance Computer performance is affected by: Registers – The size of the registers (or word size ), determines the amount of data which the computer can work at one time. Larger size means faster RAM – the larger the RAM size, the faster the computer. System clock – the faster the clock speed, the faster the computer. Bus width – the larger the bus width, the faster the computer. Cache memory – holds the most recent data and instructions that have been loaded by the CPU. The larger the cache size, the faster the computer. 46

47. 3. Computer Software Program controls the processing activity of computers. Collectively programs are called software. A blending of software and hardware gives life to a computer system. There are two categories of software: System software – essential for the computer to function; it helps the computer manage its own tasks and devices. Application software – enables user perform specific tasks. 47

48. Computer Software (cont’d) Computer software System software Application Software System management System development High level programming language Utilities Device driver Low level programming language Operating system 48

49. System software consists of: Operating system , whose tasks are: Process management - creation, deletion, suspension, resumption, scheduling and synchronization of processes. Memory management - allocation and de-allocation of memory space as required. File management - creation and deletion of files and directories. It also organizes, stores, retrieves, names and protects all the files. Device management - manages all the devices of the computer system such as monitor, printer, disk etc. Security management - protects system resources and information against destruction and unauthorized use. User interface - provides the interface between the user and the hardware. Computer Software (cont’d) 49

50. Device Drivers responsible for proper functioning of devices. part of the operating system or separate software acts like a translator between the device and programs that use the device. System Utilities help users in system maintenance tasks and in performing tasks of routine nature. These include: Formatting Defragmenting Compressing Backing up Scanning for viruses, etc. Computer Software (cont’d) 50

51. System Development Programs allow to write and construct programs. Programming language – allows to write programs. They are divided into three categories: machine language, assembly language and high level language. Language translator – convert programs written in programming language into machine language. Assembler Interpreter Compiler Linker - links together several object modules and libraries to form a single, coherent program (executable) Loader - responsible for loading and relocation of the executable program in the main memory. Computer Software (cont’d) 51

52. Application Software is used to accomplish specific tasks rather than just managing a computer system. There exist different types of application software: Word processor - a computerized typewriter. permits the electronic creation, editing formatting, filing and printing of text. E.g. Microsoft word Computer Software (cont’d) 52

53. Spreadsheet – electronic worksheet. Arranged into rows and columns, the intersection of which is called a cell. You can enter data into cells and make calculations by using formulae and built-in functions, draw different types of graphs, perform what-if analysis, and make decisions. E.g. Microsoft Excel, Lotus 1-2-3 Computer Software (cont’d) 53

54. Database Management Systems An application software that enables users: create a database, maintain it (add, delete and update its records), organize data in desired fashion, and selectively retrieve useful information from it E.g. MS Access, Oracle, etc. Graphics Software Used in creating, editing, displaying, and printing graphs, diagrams, charts, and images E.g. Corel Draw, paint, AutoCAD, etc. Computer Software (cont’d) 54

55. Relationship Between Hardware and Software System Software Hardware Application Software Application layer executes on the system software layer, which lies on the hardware layer. 55

56. Bandwidth – rate at which data is transmitted Expressed in bits per second (bps). Other units include Kilobits per second (1 Kbps = 10 3 bps) Megabits per second (1 Mbps = 10 6 bps) Gigabits per second (1 Gbps = 10 9 bps) Terabits per second (1 Tbps = 10 12 bps) Narrow band – slow rates (<256 Kbps) Broadband – high rates (>=256 Kbps) 4. Data communication & Computer Networks (cont’d) 56

57. Transmission Media Two broad categories: guided and unguided. In guided media, cable is used to guide the data flow. In unguided media, no cable exists to guide the data flow Guided media may be copper or optical fiber cables. 57

58. For data communication, we use the following copper cables: Transmission Media (cont’d) Coaxial cable – consists of a single copper conductor at its center, an outer braided metal shield and a plastic layer insulation in-between. Two types of coaxial cable are: ThinNet (or 10Base2) – where the 2 refers to the max segment length, which is 185m (200m) ThinNet cables use BNC connectors ThickNet (or 10Bas5) – where the 5 refers to the max segment length, which is 500m In both cases, the 10 refers to the max. transmission rate, which is 10Mbps Coaxial cable BNC Connector 58

59. Twisted Pair Cable – made of two or more pairs of insulated copper wires twisted together. May be unshielded or shielded (UTP/STP). UTP is the most popular and is generally the best option for most networking. It is cheap, easy to wok with and supports high transmission rate. Currently, Cat5 (100MBps), Cat6 (1Gbps) and Cat 7 (10Gbps) are in use It uses RJ-45 connectors Transmission Media (cont’d) 59

60. STP has shield to protect data from EMI and RFI. It is suitable for environments with electrical interference. The extra shielding can make the cables quite bulky. Transmission Media (cont’d) 60

61. Optical fiber cables are also used in data communications. Much longer distance than copper cables. Support higher transmission rate. Immune to interference. Transmission Media (cont’d) Connectors 61

62. Specification Cable Type Maximum length 10BaseT Unshielded Twisted Pair 100 meters 100BaseT Unshielded Twisted Pair 100 meters 10Base2 Thin Coaxial 185 meters 10Base5 Thick Coaxial 500 meters 10BaseF Fiber Optic 2000 meters Transmission Media (cont’d) Summary for guided media 62

63. Unguided media are used where guided media cannot be used. They may use: Infra-red For short distances, with no obstacle Radio wave For medium distances, say 100m Micro wave For longer distances Terrestrial or satellite communication Transmission Media (cont’d) 63

64. Networking Devices Networking devices inter-connect end devices. They include: Network Interface Card (NIC) Inserted into the computer expansion slot. provides physical, electrical, and electronic connections to the network media. Repeater extend the maximum reach of a network. receive signals on one port, amplify them, and repeat them out on the other port Hub Multiport repeater Central device in a star topology network 64

65. Bridge separates a single network into two segments. improve network performance Switch high-performance, multi-interface bridges. filter transmission of data into unintended segments. Router connects multiple networks into an internetwork. can decide how best to get network data to its destination. Networking Devices 65

66. Computer Network A computer network is a connection of two or more computers to share information and resources. Based on the area they cover, networks may be classified as: Local Area Network (LAN) – a single room, building or campus. Metropolitan Area Network (MAN) – spans a city. Wide Area Network (WAN) – spans more than one city. 66

67. Computer Networks (cont’d) WANs differ from LANs in the following ways: WANs cover greater distance. WAN speeds are slower. WAN connections can be on demand or permanent; LAN connections are permanent. Media used by WANs are typically public while those used by LANs are private. 67

68. 5. The Internet Global Interconnection of networks and computers No owner of Internet; only standards bodies Internet access is through ISP (Internet Service Provider) Internet access technologies include: Non-permanent (dial-up) connection Uses MODEM and telephone lines Permanent – connection, which includes: DSL (digital subscriber line – using telephone lines) Coaxial cable Fiber-optic Wireless 68

69. The Internet (cont’d) To establish dial-up connection, you need: An account with an ISP A telephone connection Modem ( MOdulator / DEModulator ) Communication software (e.g. Internet browsers such as Internet Explorer and Mozilla Firefox) Advantages of dial-up connection: Is not costly to connect It flexible Small monthly payment Disadvantage Low speed and connection set-up time 69

70. The Internet (cont’d) Advantages of the permanent connection Faster speed Fixed monthly payment Disadvantages of the permanent connection Higher cost than dial-up Not flexible, except for the wireless 70

71. Internet Protocols Protocol – set of rules that govern the communication between computers in a network. In the Internet, there exist a set of protocols organized in a layered architecture. The set of protocols is called “Protocol suite”. The Protocol Suite in the Internet is TCP/IP (Transport Control Protocol/Internet Protocol) 71

72. Internet Applications Some of the applications running on the Internet include: The World Wide Web (WWW) Electronic Mail (e-Mail) File Transfer Protocol (FTP) Telnet Chat and Instant Messaging Internet Telephony Video Conferencing Etc. 72

73. Internet Applications (cont’d) The World Wide Web (WWW) A vast collection of documents stored Web Servers Web pages contain Different types of documents: text, image, audio, video Links to other web pages Hypertext Mark-up language (HTML) is used to design a web document It uses the HTTP (Hyper-Text Transfer Protocol) The web is interactive – you can fill up forms on-line, run applications, select options 73

74. Internet Applications (cont’d) Web browser – program than runs on the computer requesting for web content (e.g. Internet Explorer) or the computer itself. Web server – program that runs on the computer that hosts the web page (e.g. IIS or Apache) or the computer itself. URL (Uniform Resource Locater) – shows the exact location of a web content/resource. http :// www . webopedia.com / TERM/U/ URL .html Protocol Host Domain Path 74

75. Internet Applications (cont’d) To use a web browser: Get connected to the Internet. Start the Wed browser application. Type the URL in the address box, or Type the address of one of the webs that have searching facilities, e.g. www.google.com and then type in a search text/phrase search for box and press Enter. Use the hyperlinks to jump to other pages. 75

76. Internet Applications (cont’d) E-Mail (Electronic Mail) One of the most widely used Internet applications. Used to send/receive messages electronically can transmit text, images, audio and video clips. Allows users to send a message to just one user or a group of users. Large documents can be attached. Users can read, print, forward, answer or delete a message. Itl is much cheaper and faster in comparison to other communication services. Each E-mail user is assigned a unique address, which is used by the e-mail network to deliver the message. You need to have e-mail account with e-mail service provider E-mail addresses are of the format: User_name@provider_name , e.g. [email protected] 76

77. Internet Applications (cont’d) FTP (File Transfer Protocol allows a user to transfer data/files between computers on the Internet. Provides commands that allow users to manage files. Telnet Allows you to log into computers on the Internet and then enter commands which will be executed as if you were entering them directly on the server. To use Telnet to connect to remote computer, you must know its address. E.g. Telnet 140.147.254.3 77

78. Internet Applications (cont’d) Usenet News It is a global electronic bulletin board system in which millions of computer users exchange information on a vast range of topics. Usenet messages are stored on central computers, and users must connect to these computers to read or download the messages posted to these groups. There are thousands of Usenet newsgroups. These range from academic to recreational topics. Serious computer-related work takes place in Usenet discussions. 78

79. Internet Applications (cont’d) Chat It is a way of talking online in realtime with many people at once. Some chat rooms are available via the Web, such as Yahoo! Chat , while others require a separate software program for chatting with other users. Online chat rooms allow multiple users to join in a conversation and see what all the other people are typing. Many chat rooms focus on a particular topic or interest . Instant Messaging IM is a way of communicating online with a select group of people, usually individually. To instant message someone, you need to know his or her screen name. IRC Kind of group chatting Provides a way of communicating in real time with people from all over the world. It consists of various separate networks (or "nets") of IRC servers, machines that allow users to connect to IRC. 79

80. Internet Applications (cont’d) Internet Telephony Uses the Internet for telephone conversation For users who have free, or fixed-price Internet access, Internet telephony software essentially provides free telephone calls anywhere in the world. To date, however, Internet telephony does not offer the same quality of telephone service as direct telephone connections. Skype is a popular Internet Telephone application 80

81. Internet Applications (cont’d) Video Conferencing Allow two or more locations to communicate by simultaneous two-way video and audio transmissions. Differs from videophone calls in that it's designed to serve a conference or multiple locations rather than individuals. Applications include teaching/learning Teleconferencing Allow two or more locations to communicate by simultaneous two-way audio transmissions. 81