A web application is a software program that runs on a web server, and is accessed through a web browser over the Internet. Web applications are typically written in programming languages such as HTML, CSS, and JavaScript, and may use other technologies such as PHP, Ruby on Rails, or ASP.NET. They can be interactive and dynamic, and can include features such as databases, user accounts, and e-commerce functionality. Web applications are often used for tasks such as online shopping, social networking, and content management.