An Application Server is a software framework that provides an environment for running applications. It acts as a mediator between the user interface and the backend database, enabling the execution of business logic and processing requests. This server supports various programming languages and frameworks, making it versatile for different types of applications. Application servers often include features like load balancing, security, and transaction management, which enhance performance and reliability. They are commonly used in web applications, where they handle requests from users and deliver dynamic content. Examples of application servers include Apache Tomcat, JBoss, and IBM WebSphere.