Full stack development involves working on both the front-end and back-end of web applications. A full stack developer is proficient in all layers of development, including the client-side (front-end), which focuses on the user interface and user experience, and the server-side (back-end), which handles application logic, databases, and server interactions. Full stack development encompasses a broad range of technologies, tools, and programming languages, allowing developers to build and maintain complete web applications from start to finish.