IIS, or Internet Information Services, is a web server software created by Microsoft. It is used to host and serve websites and applications on the Windows operating system. IIS supports various protocols, including HTTP, HTTPS, and FTP, allowing users to access web content securely and efficiently. IIS provides features like security, performance monitoring, and application management, making it suitable for both small and large-scale websites. It also supports various programming languages, such as ASP.NET, enabling developers to create dynamic web applications. Overall, IIS is a powerful tool for managing web services on Windows servers.