Cat 1E cable on Amazon.comCAT1 is typically telephone wire. This type of wire is not capable of supporting computer network traffic and is not twisted. It is also used by phone companies who provide ISDN, where the wiring between the customer's site and the phone company's network uses CAT 1 cable.
CAT2, CAT3, CAT4, CAT5 and CAT6 are network wire specifications. This type of wire can support computer network and telephone traffic. CAT2 is used mostly for token ring networks, supporting speeds up to 4 Mbps. For higher network speeds (100Mbps plus) you must use CAT5 wire, but for 10Mbps CAT3 will suffice. CAT3, CAT4 and CAT5 cable are actually 4 pairs of twisted copper wires and CAT5 has more twists per inch than CAT3 therefore can run at higher speeds and greater lengths. The "twist" effect of each pair in the cables will cause any interference presented/picked up on one cable to be cancelled out by the cable's partner which twists around the initial cable. CAT3 and CAT4 are both used for Token Ring and have a maximum length of 100 meters.
CAT6 wire was originally designed to support gigabit Ethernet (although there are standards that will allow gigabit transmission over CAT5 wire, that's CAT 5e). It is similar to CAT5 wire, but contains a physical separator between the 4 pairs to further reduce electromagnetic interference.