Raspberry Pi isn't limited to a single server application, but the most popular and easy to install seems to be Apache. Apache has been around since 1995 and caught on the next year.

To actually let folks outside your LAN use your Web server requires only a single opening—if you have a NAT router, like most home users, you need to forward TCP port 80 to your Web server.

With Windows Server 2012 R2, Microsoft has built in a reverse-proxy feature. The Web Application Proxy securely publishes internal resources out to the Internet for access by both corporate-owned ...