If you want to build a game server, you generally have several different options available to you. The two main methods are to use a computer that is connected to your home or business Internet connection, or to make use of a data center. A game server that you run out of your house or business can either use an extra computer that you already have, or you can build one from scratch. If you build a game server from the ground up, it generally needs everything any other computer does except for a graphics card. When using a data center, you can either colocate your own machine, use a managed hosting service, or rent a dedicated server box.
The least expensive way to build a game server is to make use of a computer or components that you already have. Begin by checking with the publisher of the game in question to see what the system requirements are. If there is a lack of information, you can inquire with other people that are already successfully running servers. In some cases you may find that an older computer that you no longer use will be capable of running the server, though you may need to upgrade some components. It is also fairly common for publishers to provide a Linux binary of the game server files, so you can save some money by not paying for an operating system (OS) for your server box.
If you don't have any computers or components already, you will need to shop around for parts. To build a game server that will run out of your house, you will typically just want to purchase a regular or mini tower case. You will also need components such as a motherboard, central processing unit (CPU), random access memory (RAM), and hard drive. A game server does not require a graphics card, though you may need to install one if you do not know how to operate a computer remotely.
Another option when you build a game server is to colocate it in a data center. When you build a server box for this purpose, you will typically need to use a case that is rack mountable. Since you will typically only interact with the server remotely, there is no need for a video card. All of the other typical computer components are still required.
Instead of building your own server and placing it in a colocation data center, you may choose to use managed or dedicated server hosting. If you do this, you can typically install the game server binaries on a machine that someone else is responsible for building and maintaining. An easier option is to rent a dedicated game server. Most game service providers (GSPs) offer dedicated rentals on a monthly basis, provisioned according to how many players you would like to host at a time.