Also known as a hard disk, or HD, this is where your programs, documents, music, photos, and videos are stored.
Bigger is better. Hard drive sizes are measured in gigabytes and terabytes, and commonly range from 250GB to more than 1TB (terabyte).
Though size matters, speed is equally important. Speed is measured in rpm (revolutions per minute). A slow hard drive will take longer to start up the OS and programs, and complete tasks (such as installing programs or scanning your hard drive for viruses).
For best performance, get a desktop with at least a 7,200rpm hard drive and a laptop with a 5,400rpm hard drive.
Hard drives often fail after a while, so you must back up your data periodically to avoid losing it. The best option is an external hard drive, which connects to your computer through its USB, FireWire, or eSATA port.
Some high-end desktops and laptops can be configured with a RAID (redundant array of independent disks) setup. These computers have two or more hard drives. There are several types of RAID, the most common being RAID 0 and RAID 1.
RAID 0 distributes your data across multiple hard disks, which can greatly improve speed. But if one fails, you'll lose data on all your drives. RAID 1 automatically copies data from one drive to the other. If one crashes, all your data will be safe on the other.
A service that could ease the agony of a crash is cloud computing. With a backup solution such as Carbonite, all your data resides on the company's servers. Any documents, files, data, applications, and e-mail you put on Carbonite will be available to other computers, as well as iOS, Android, and Blackberry devices.
Solid-state drives (SSDs, also called flash drives) are a newer type of storage technology, letting your computer access data without the moving parts required by a traditional hard drive.
SSDs don't have the spinning disk of a conventional hard drive, so they use less power, work quieter, and should be more resistant to damage from rugged use. And because there are no moving parts, they promise quicker access to data.
But they still cost several times that of traditional hard drives and have smaller capacities. Lower-priced hybrid drives, which combine a hard drive with solid-state memory, represent a good compromise.