Compact Disc (CD) - A small, round, portable medium used to store and play back computer data such as video, text, audio and other digital forms.

CD-ROM (Compact Disc - Read Only Memory) - A CD that stores data and can be accessed but cannot be written to.

CD-R (Compact Disc - Recordable) - A CD format that allows you to record data onto compact discs or CDs ensuring that regular CD-ROM drives can read it. Data can only be written once on these discs.

CD-RW (Compact Disc - Rewritable) - A compact disc format that can be written to many times. The disc can be erased and reused to store more information.

CD-ROM drive - A computer peripheral that allows you to play back CD-ROMs or CD-Rs.

CD-R/RW drive – A computer device that allows you to record information onto a CD. CD-R drives, commonly known as "burners", can write to recordable discs (CD-Rs) one time only. They do this by using a laser beam to "burn" data into the surface of the disc. These discs can then be read in other CD-R or CD-ROM drives. A CD-RW drive acts in the same way as the CD-R drive, but gives you the capability to erase and re-record information onto a CD-RW disc. A CD-RW drive can read all CD formats (ie. CD-ROM, CD-R and CD-RW); however, CD-RW discs cannot always be read in CD-ROM or CD-R drives.

Client – A client is a customer to whom a service is provided. In a networked environment, a client is a computer (or software running on a computer) that requests information and/or services from a server.

Compression – The shrinking in size of data to save space or the amount of time transmission takes. Common compression formats include zip and rar. Various utilities are available that allow you to compress your data to different degrees.

Cookie – A piece of data given to your browser by a web server while you are viewing web sites. This data is stored on your hard drive and allows the web site to identify you.

Central Processing Unit (CPU)– More commonly known as a processor, this is the unit inside your computer that carries out instructions given by a program. It is the "brain" of the computer. Some people refer to the entire computer case as the CPU.

Ctrl – Control Key. This key is located at the left and right ends of the bottom row of most standard keyboards. When working with some programs, this key can be combined with others to create shortcuts or "hot keys" to functions. Example: Holding the Ctlkey down and pressing S will save the file you are currently working in (Windows only). For more shortcuts and useful tips, check out our How To... section.