Fingerspelling is the process of spelling out words by using signs that correspond to the letters of the word. An ASL user would use the American Fingerspelled Alphabet, (also called the American Manual Alphabet). There are many different manual alphabets throughout the world. The American Fingerspelled Alphabet consists of 22 handshapes that--when held in certain positions and/or are produced with certain movements-- represent the 26 letters of the American alphabet.
When should you use fingerspelling? There are lots of times when fingerspelling is used. The typical "these things are spelled" list includes such items as: - people's names - places - titles - brands
Why not use fingerspelling instead of ASL signs? People often ask why not just use fingerspelling instead of American Sign Language, that way you would only have to learn 26 signs, and more people would be able to understand. That is a good point, but it would be impractical just to use fingerspelling. Conversations would take hours, and it would be very hard to add feeling and expression to a conversation that just used fingerspelling.