Whether you want to search through an entire set of encyclopedias (which can be stored on one CD-ROM disk), see a lion up close and personal (and then hear it roar) or view the text of a John F. Kennedy speech (and even watch him deliver it on-screen), a CD-ROM drive is the answer.

The disks used for CD-ROM drives look just like audio CDs. CD-ROM disks are capable of doing two things: writing data to and reading data from (R); and rewriting data to/from (RW). These disks are referred to as CD-R and CD-RW respectively. They perform their tasks much like a floppy disk or hard drive. There are also two types of RW disks to choose from: +RW and -RW. Which media to choose is dependant upon your CD Drive . The process of putting new information onto a CD-R or CD-RW is called "burning" or "ripping".

CD-ROM drives come either as internal or external units, and are viewed by your computer as another storage drive on the system.

Another type of disk player is the DVD-ROM drive. These are CD-ROMs on steroids. The original and most widely available models today store up to 4.7 gigabytes of data -- about eight times as much as current CDs. Models new and in stores now offer 8.2 gigs of storage and can also have labels created on them directly from the DVD unit itself. That means they store and play full-length motion pictures on your computer or TV set. Since the new drives are compatible with older CDs, you can expect them to show up first in high-end computers. .

Meanwhile, here are some of the characteristics that differentiate one model of standard CD-ROM drive from another:

Spin speed. Also known as the transfer rate, spin speed refers to how fast the disk spins, setting an upper limit for how fast data can be transferred from the disk. This speed is measured in multiples of the original, "single-speed" CD-ROM, which could spit data out at 150 kilobytes per second.

Access time. This number reflects the average time it takes the laser pickup -- the CD-ROM drive equivalent of a magnetic disk-drive head -- to reach a location on the disk. The higher the number, the slower this process, so a drive with a 120-millisecond access time is better than a drive with a 250-millisecond access time.

Cache buffer. This is extra random access memory (RAM) within the CD-ROM drive that is used as a holding area for data that has been pulled off the disk. Because information can be transferred more quickly from memory than from the disk, a cache buffer can crank up the performance of a CD-ROM drive: The computer yanks the data from the cache buffer instead of re-reading it from the disk. The larger the buffer size, the more data it can hold, and the faster the drive will perform.