Hard drive is the computer hardware that contains an optical and/or magnetic disk, which it both writes and reads data on; it stores all electronic information and software programs, making it one of the most important components of a computer. Hard drive capacity is measured in bytes, both megabytes (MB) and gigabytes (GB). 1 GB equals 1, 024 megabytes. Standard hard drives range from 40 GB to above 120 GB. 40 GB has become the standard for PC hard drives. Those who DON’T use their PC to manage their day to day activities or download a lot of new software programs, photos or other items that take up space would be fine with a standard capacity hard drive. Those who DO perform all the previously mentioned activities should buy a PC with a greater hard drive capacity.