A Web Container, also known as a Servlet Container or a JSP Container, is a software component that runs web applications on a web server. It provides a runtime environment for web components such as servlets, JSPs, and filters to run in. The web container manages the life cycle of these components, provides security, and handles requests and responses between the server and the client. In essence, it acts as the bridge between the application and the web server, allowing web applications to function and communicate with clients through HTTP. A thorough understanding of Web Containers is essential for web developers and system administrators dealing with web-based applications.