WebSphere Application Server is a software platform developed by IBM that allows businesses to build, deploy, and manage web applications. It provides a robust environment for running Java applications and supports various programming models, making it suitable for enterprise-level solutions. The server is designed to handle high traffic and offers features like security, scalability, and reliability. It supports various web services and integrates easily with other IBM products, enhancing its functionality for developers and IT teams. Overall, WebSphere Application Server is a key tool for organizations looking to streamline their application management processes.