When they think of servers, many people imagine a room sized giant computer like this:
Cool. This could run a banking system or a giant network.
Computers like this are generally obsolete and aren't used much any more.
Most servers are PC computers, just like the ones we have in our classroom lab. Any computer can be a server, if it distributes information to other computers over the internet.
What makes a computer a server, is more how you use it, than what kind of computer it is. If you use a computer to distribute information, usually over the internet, then it is a server.
Here's a more typical modern server:
This computer is really big and has room for several hard disks. You could store a giant SQL database or a mail server on a computer like this.
That's nice, but it usually isn't required.
Modern hard disks are pretty big, so we usually don't need the space from several hard disks.
The giant case size doesn't get you much. Computers are usually pretty much full of air. Buying big bulky computers doesn't make much sense.
We used to use computers like this, but they take up too much power and too much space. So at Brand X Internetwe've been getting rid of the big servers and replacing them with smaller power efficient computers that look like this:
The picture is life size. This server is about five inches across and it does everything we need.
Note: many people say "server" when they mean "internet provider". That's wrong. A server is a computer. An internet provider is a company that provides you Internet access.
So the server is really just a PC. What makes it a server is the function. A server is a computer that distributes information over the network.
What really makes a server is the software. Most any computer will do for a server. I will discuss four kinds of servers: unix, windows, linux, and mac.
Originally most Internet servers were running Unix. There is a strong connection between Unix and Internet functions. Email and ftp and telnet, the most popular service on the original internet, before the web was developed, were all Unix functions that were adapted to work over the internet.
Popular Unix servers were manufactured by HP, Sun, Silicon Graphics, and many companies. All of these computers were workstations or mainframe computers running one or another version of the Unix multiuser operating system, which was developed with financing mostly from the US Military.
Unix based servers usually run the following:
All of these companies made really great servers, but because of the high cost, these Unix computers are now largely out of favor.
Some companies now use FreeBSD, a free version of Unix which generally works pretty well and can be installed on any PC.
Linux strictly speaking is not Unix but it is a Unix clone. A Finnish student named Linus Torvalds took the specifications for Unix and wrote a new program that did exactly the same thing. His version was so good it has largely replaced UNIX for servers on the Internet. Linux is free. You can simply download it and install it on your computer. Currently the most popular versions are Redhat (Fedora) and Ubuntu.
Linux offers the same server software as Unix.
Because PC computers are cheap, and Linux free, many companies that operate popular web sites use "server farms" of dozens or hundreds of inexpensive linux based computers, instead of the old Mainframe computers. Examples of websites using this kind of hardware and sofware are Amazon, Facebook, and most other popular sites.
At Brand X Internet, we generally use Linux based servers.
With in about 1995 Microsoft recognized the importance of the Internet and built Internet capability into both its server and client computers in Windows NT. Much improved versions came with Windows 2000. Up to that time you had to get separate drivers and software to connect a Windows PC to the Internet. At Leonardo Internet in 1995 we used to send out little floppy disks with drivers to customers who were signing up. That wasn't necessary any more when Microsoft started including those drivers with their software.
Current versions of Windows support the following Internet server programs:
All you have to do to convert a Windows computer to a server is install one of these programs.
Windows servers generally work well and are in use throughout the Internet.
Advocates say the Windows computers are reliable and easy to set up, and generally use a drag and drop windows based configuration system. Windows administrators don't like the configuration files that are usually used with Unix based servers.
Windows has a nice set of programming tools that are compatible with its server products, called ".net" (say "dot net"). These make it easy to build websites with e-commerce features, so you will often see Windows servers running various catalog or database driven sites.