Web applications are software programs that run on a web server and can be accessed through a web browser. Unlike traditional desktop applications, they do not need to be installed on a user's device. Users can interact with these applications over the internet, making them convenient for tasks like online shopping, banking, and social networking. These applications are built using technologies such as HTML, CSS, and JavaScript. They often rely on databases to store and manage data, allowing for dynamic content and user interactions. Popular examples of web applications include Google Docs, Facebook, and Amazon.