Categories 1 through 6 are based on the EIA/TIA-568-B standards.
On the newer wiring for LANs is CAT5e, an improved version of CAT5 which used to be outside of the standard, for more information on twisted pair, please see: twisted pair.
Category Cable Type Mhz Usage Speed
============================================= CAT1 UTP Analog voice, Plain Old Telephone System (POTS) CAT2 UTP 4 Mbps on Token Ring, also used on Arcnet networks CAT3 UTP, ScTP, STP 16 MHz 10 Mbps CAT4 UTP, ScTP, STP 20 MHz 16 Mbps on Token Ring Networks CAT5 UTP, ScTP, STP 100 MHz 100 Mbps on ethernet, 155 Mbps on ATM CAT5e UTP, ScTP, STP 100 MHz 1 Gbps (out of standard version, improved version of CAT5) CAT6 UTP, ScTP, STP 250 MHz 10 Gbps CAT7 ScTP, STP 600 M 100 Gbps
Category 6 has a minumum of 250 MHz of bandwidth. Allowing 10/100/1000 use with up to 100 meter cable length, along with 10GbE over shorter distances.
Category 6a or Augmented Category 6 has a minimum of 500 MHz of bandwidth. It is the newest standard and allows up to 10GbE with a length up to 100m.
Category 7 is a future cabling standard that should allow for up to 100GbE over 100 meters of cable. Expected availability is in 2013. It has not been approved as a cable standard, and anyone now selling you Cat. 7 cable is fooling you.
REFERENCES: http://donutey.com/ethernet.php http://en.wikipedia.org/wiki/TIA/EIA-568-B http://en.wikipedia.org/wiki/Category_1_cable