Internet Information Services (IIS) is a web server software developed by Microsoft, designed to host and manage websites, web applications, and services on Windows servers. It is tightly integrated with Microsoft technologies like .NET, ASP.NET Core, PowerShell, and Azure, making it a preferred choice for Windows-centric environments.

IIS operates by listening for client requests (via protocols like HTTP/HTTPS) and responding with the requested content, such as web pages, APIs, or files. It supports both static content (e.g., HTML, CSS) and dynamic content (e.g., ASP.NET, PHP, Python) through its extensible architecture.