A Web server is a computer system that hosts websites. It runs Web server software, such as Apache or Microsoft IIS, which provides access to hosted webpages over the Internet. Most Web servers are connected to the Internet via a high-speed connection, offering OC-3 or faster data transmission rates. A fast Internet connection allows Web servers to support multiple connections at one time without slowing down.
Any computer can be used as a Web server, as long as it is connected to the Internet and has the appropriate software installed. However, most Web servers are 1U rack-mounted systems, meaning they are flat, trimmed down computers that can be mounted on a server rack. Most Web hosting companies have several server racks, which each contain multiple servers. This is the most space-efficient way to host a large number of websites from a single location.
Web servers typically host multiple websites. Some only host a few, while others may host several hundred. Web servers that host websites for multiple users are called "shared hosts." This is the most common type of hosting solution and is used for personal sites, small business sites, and websites run by small organizations. Web servers that only host websites for a single person or company are called "dedicated hosts." These types of servers are appropriate for high-traffic websites and sites that require custom server modifications. Dedicated hosts are also more reliable than shared hosts, since there are fewer sites that can cause bottlenecks or other issues with the server.