UTP (unshielded twisted pair) is the most common cable used in networks today. Some less-common, but worth-knowing-about cable include
STP (shielded twisted pair)— Used for Token-Ring (very obsolete) and older wide-area applications.
Fiber (fiber-optic cabling)— Completely immune to electromagnetic interference, high distance limitation, has the highest theoretical (and practical, as of this writing) data rate possible. Tough to work with because it requires special (and reasonably expensive) equipment.
For our purposes here, we will assume that UTP is in use in your network, which is subcategorized as CAT-3 and CAT-5, and is used for 10Mb (megabit) and 100Mb Ethernet, respectively. The newer CAT-5e (pronounced Cat-Five-E) ...