Understanding the PyTorch Code This code implements a simple convolutional neural network (CNN) for image classification using PyTorch. Let's break down the code section by section. First, necessary libraries are imported: torch for tensor operations, torch.nn for neural network modules, torch.optim for optimizers, and torchvision for datasets and transformations. A custom CNN model, ConvNet , is defined using nn.Module . It consists of convolutional layers ( conv1 , conv2 ), max pooling ( pool ), and fully connected layers ( fc1 , fc2 ). The forward method specifies the flow of data through the network. The code then initializes the model, loss function ( nn.CrossEntropyLoss ), and optimizer ( optim.Adam ). The CIFAR-10 dataset is loaded using torchvision.datasets , transformed into tensors, and divided into training and testing sets using torch.utils.data.DataLoader . The training loop iterates through the training data, performs forward and backward passes, and updates the model's weights using the optimizer. The batch loss is printed periodically. Finally, the model is evaluated on the test data, and the overall accuracy is printed. import torch.nn as nn import torch.optim as optim from torchvision import datasets, transforms class ConvNet(nn.Module): def __init__(self): super().__init__() self.conv1 = nn.Conv2d(3, 32, 3) self.pool = nn.MaxPool2d(2, 2) self.conv2 = nn.Conv2d(32, 64, 3) self.fc1 = nn.Linear(64 * 6 * 6, 128) self.fc2 = nn.Linear(128, 10) def forward(self, x): x = self.pool(torch.relu(self.conv1(x))) x = self.pool(torch.relu(self.conv2(x))) x = torch.flatten(x, 1) x = torch.relu(self.fc1(x)) return self.fc2(x) model = ConvNet() criterion = nn.CrossEntropyLoss() optimizer = optim.Adam(model.parameters()) train_data = datasets.CIFAR10('./data', train=True, download=True, transform=transforms.ToTensor()) test_data = datasets.CIFAR10('./data', train=False, download=True, transform=transforms.ToTensor()) train_loader = torch.utils.data.DataLoader(train_data, 4, True) test_loader = torch.utils.data.DataLoader(test_data, 4, False) for epoch in range(10): for batch, (data, target) in enumerate(train_loader): optimizer.zero_grad() loss = criterion(model(data), target) loss.backward() optimizer.step() if batch % 100 == 0: print(f"Epoch {epoch} [{batch * len(data)}/{len(train_loader.dataset)} ({100 * batch / len(train_loader):.0f}%)] Loss: {loss.item():.6f}")