Not enough space on your hard drive to store all those cool images you shot of the family with your digital camera, or to save those neat games you found on the Web?

Think of a hard drive as the space you have to store your clothes at home. Whether it be in closets or in drawers, there never seems to be enough space, and you find yourself constantly buying plastic crates and other storage goodies that fit under beds and places never thought of before. You can never really buy a hard drive with "too much" memory. Hard Drives are used to store files, add software, and download images and web pages. Hard drive capacity is measured in Megabytes (MB) or Gigabytes (GB). So while shopping for a hard drive, the key is to buy as many gigabytes as your budget allows. Hard drives may be internal or external.

Internal
Every desktop or notebook computer comes with some kind of internal hard drive already built in. The average capacity for new desktop computers is about 20GB and 6GB for notebook computers. Internal hard drives reside within a computer body, and are usually not very visible. If there is an available internal drive bay, more hard disk storage space may be added to most computers by installing an additional hard drive, or replacing the old one. The additional hard drive may operate alone or along side the built-in drive. Internal hard drives are less common with notebook computers. Some notebook computers don't allow a replacement or an addition of hard drives.

External
Like internal hard drives, external hard drives may be added to any desktop or notebook computer. External drives connect to any notebook computer via a USB or FireWire port. The drive itself is rectangular shaped and can usually sit on top a desktop tower, or along side a notebook computer.

The hard drive stores everything from software, websites, email to music, images and text. Stick with somewhere between 4-9GB if you plan to use light software and will primarily save text, email and occasional photos. If you create graphics, have a digital camera or a scanner, use graphic intensive software, save MP3s and VideoStream web files, you want to shoot for a hard drive capacity of 20GB or more.

All hard drives have a RPM or Rotations Per Minute rate. Not to get too technical now, but there are pieces inside each drive that spin to read or store data. The faster they spin or rotate, the quicker you can retrieve and store files from and onto your hard drive. The average hard drive as an RPM of up to 5,400, and a superb pace is up to 7,200RPM. Some hard drives for servers can reach up to 10,000RPM. Faster drives work better when used with compatible applications.

If you're replacing a drive you do want to make sure that the new hard drive will fit in place, of the old one, if you plan to place it in a bay. For desktops, a drives physical measurement is usually 3.5 inches and 2.5 for notebooks. Some internal notebook drives may be impossible to replace, so you'd have to get an external one. You never want to risk loss of information, so never replace a drive unless you've transferred data onto the new drive or have back-ups.

Your built-in hard drive is usually connected to your motherboard via a 40pin cable connector. Most desktop PC's have an internal EIDE interface, which may have available connection for expansion. External hard drives may come with one (or 2) connection port like Parallel, USB, FireWire, SCSI or PCMICIA. SCSI interfaces are more common for networks and external connections.