Built desktop hard drive?

[Viking1977]

I have a built computer that I bought on Ebay about a year ago. It only has a 250 gb hard drive, I want to upgrade it to make the computer faster, how do I know what hard drive to buy? Do they all fit the same in desktops?

 

[johnb35]

Any desktop hard drive will work. However, you really want faster system then get an ssd drive and use your existing drive as storage.