IIS (Internet Information Services) is one of the most popular and dependable options for hosting and administering web applications on Windows servers. Microsoft created IIS, a versatile, safe, and controllable web server for hosting websites, services, and apps.

IIS: What is it?
A web server software program called IIS (Internet Information Services) is made to provide users with web pages and applications via the internet or an intranet. In addition to being closely linked with Microsoft technologies like.NET, ASP.NET Core, PowerShell, and Azure, it is incorporated into the Windows operating system. Fundamentally, IIS handles client browser requests (via HTTP/HTTPS), waits for them, and then returns the requested content (such as HTML, pictures, APIs, etc.).

Key Features of IIS

Web Application Hosting

  • Supports ASP.NET, .NET Core, PHP, Node.js, Python (via extensions).
  • Handles static files (HTML, CSS, JS) and dynamic content.

Protocol Support

  • HTTP/HTTPS
  • FTP/FTPS (File Transfer Protocol)
  • SMTP (for emails)
  • WebSockets

Security

  • SSL/TLS certificates for secure connections.
  • IP restrictions, request filtering, authentication, and authorization options.

Scalability & Performance

  • Application Pools to isolate applications.
  • Load balancing and caching support.
  • Integration with Windows Process Activation Service (WAS) for non-HTTP protocols.

Extensibility

  • Modular architecture allows enabling/disabling specific features.
  • Supports third-party modules for added functionality.

Administration Tools

  • IIS Manager (GUI).
  • Command-line (appcmd).
  • PowerShell integration for automation.

How IIS Works (Simplified)

  1. Client Request – A user enters a URL in the browser.
  2. DNS Resolution – Domain name resolves to the IIS server’s IP address.
  3. IIS Receives Request – IIS listens on port 80 (HTTP) or 443 (HTTPS).
  4. Request Processing – IIS checks application pools, routes to appropriate handler (e.g., ASP.NET pipeline).
  5. Response – IIS sends back the requested page or API response to the browser

Real-World Use Cases of IIS

  • Corporate Websites – Host internal and external websites on Windows servers.
  • Enterprise Applications – Run ASP.NET and .NET Core applications.
  • APIs and Web Services – Expose REST APIs for mobile and web apps.
  • FTP Hosting – Secure file sharing within organizations.
  • Load Balanced Environments – IIS servers work behind a load balancer for high traffic apps.

Advantages of IIS

  • Seamless integration with Windows and .NET technologies.
  • Easy-to-use GUI for administration.
  • Strong security features.
  • Scalable for small to enterprise-level applications.

Alternatives to IIS
While IIS is powerful, other web servers exist:

  • Apache HTTP Server (popular in Linux environments).
  • Nginx (high-performance and lightweight).
  • Tomcat (for Java applications).
  • IIS stands out when the environment is Windows-centric and applications are built with Microsoft technologies.

Conclusion
Millions of websites and business apps around the world are powered by IIS, a reliable, secure, and adaptable web server. IIS offers the tools and integration required to manage and expand web hosting on Windows, regardless of the size of the application—from a small business website to a large-scale.NET application.