Generative Adversarial Networks (GANs) use two neural networks, a generator and discriminator, that compete against each other. The generator learns to generate fake images that look real, while the discriminator learns to tell real images apart from fakes. This document discusses various GAN architectures and applications, including conditional GANs, image-to-image translation, style transfer, semantic image editing, and data augmentation using GAN-generated images. It also covers evaluation metrics for GANs and societal impacts such as bias and deepfakes.