A server is a computer that receives a request from another computer across the internet and then fulfils that request. There are many different types of server. For example:
The most important type of server though, is the web server. Web servers host websites. Every website needs at least one server to host it. As you’re visiting Phoenix Web Development, this is most likely the type of server you’re interested in.
Any computer can be turned into a web server and even used for other tasks at the same time. It simply needs the correct software installed and a connection to the internet. However, most servers are operated by specialised web hosting companies on dedicated hardware. These companies leverage economies of scale to provide hosting cheaper than you could ever do it yourself.
The majority of the world’s web servers are setup on Apache Server software. On its own, Apache Server allows you to serve static websites. To serve modern dynamic websites, a combination of software packages is required. The most common combination is the LAMP stack. LAMP is a tried and tested solution which has worked for websites for decades. It is far from the only way to host a website however. Any program making up the acronym can be swapped out for another equivalent program. Entirely different paradigms also exist for serving dynamic websites, such as Microsoft’s IIS ecosystem and the newer MEAN.
You can learn more about servers at Wikipedia’s server article.