One of the advantages of building your own computer is that you can pick and choose all the components to deliver the performance you want. The problem is that you are spoiled for choice with the variety of components, such as computer motherboards, that you can choose from.
It is important to choose correctly when buying computer motherboards, since the motherboard will dictate what options you have with the rest of the devices you will need in the computer.
The CPU is the heart of your computer system, and ultimately controls everything else. When you buy computer motherboards, you can buy them with a CPU already on board. Alternatively, you can source and fit your own CPU. However, you must source a CPU that is compatible with the motherboard.
There is a temptation to go and buy the fastest, newest CPU, but you should really give some thought as to what you will be asking your computer to do, and then buy enough power to handle those tasks with maybe a bit extra left over. The more modern and powerful a CPU is, the more it will cost. If you are into 3D gaming, then buying power is your best option. In contrast, if you intend to use your computer to run office type applications or just to surf the Internet, you can save money by buying a lower specification CPU.
You need to analyze your total requirements before researching motherboards. You must know what devices you will be connecting so that you can narrow down your choice to those motherboards that have the physical capability to let you attach your devices. Do you want multiple USB connections, or can you get by with just a couple?
If you are upgrading an existing motherboard, you will need to get one that is compatible with your existing CPU, RAM, and other devices. Otherwise, you will end up having to replace these as well.