CAT 6 (short for Category 6) refers to an Ethernet cable as defined by Electronic Industries Association and Telecommunication Industry Association (EIA/TIA). Like its name suggests, CAT 6 is a sixth generation of twisted pair Ethernet cabling. The cable itself contains four pairs of copper wire and utilizes all of them, unlike the earlier version, the CAT 5. CAT 6 supports Gigabit Ethernet and supports communications much faster (about twice) than the CAT 5e, the other standard for Gigabit Ethernet cabling. It also features more stringent specifications for crosstalk and system noise. This cable may be identified by the printing on the side of the cable sheath. CAT 6 supports 10BASE-T/100BASE-TX as well as 1000BASE-T (these are IEEE standards that define the requirement for sending information at various speeds as well as various aspects of running baseband Ethernet on the cabling) and may in the future support 10GBASE-T (10 Gigabit Ethernet) though there will be limitations as regards the length if the unshielded CAT 6 cable is used. As is usual with all other types of twisted pair EIA/TIA cabling, CAT6 cables are limited to a maximum run rate of 100m (328 feet).

The CAT 6 cable is being made with 23 gauge conductor wire as opposed to the slightly smaller 24 gauge that is used to make CAT 5. However, using 23 gauge conductor is not really a requirement, and its possible to make a CAT 6 cable with 22 or 23 AWG gauge wire for ANSI/TIA-568-B.2-1 specifications, provided the cable can meet the required specifics standards. CAT 6 cable is normally terminated in 8P8C modular connectors when used as a patch cable. CAT 6 connectors are made to lofty specifications that aid in reducing noise caused by crosstalk as well as system noise. Significantly, attenuation, Near End Crosstalk (NEXT) and Power Sum Next (PSNEXT) are lower when compared with CAT 5 or CAT5e.

Some varieties of CAT 6 cables may be too big and it becomes tricky to attach to 8P8C connectors without using a special modular piece. Such cables ate technically not standard. Should one mix the components of various cable standards, this will result into sub-optimal performance of the signal path which will be reduced to the lowest category. The cable is terminated in T568A or T568B schemes, and it matters a little as to which scheme is used since both schemes (though T568B is more widely used) are both straight through (meaning pin 1 will go to 1, pin 2 to 2 and so on). Any mix-up of the terminating patch codes between the two schemes does not produce pinout problems in a facility. It may, however, slightly degrade the quality of the signal even though the effect of this is marginal.

Twisted pair cable like the CAT 6 come in two main varieties-stranded and solid. The solid one supports the longer runs and performs best in fixed wiring configurations like those that are found in office buildings. The stranded AT 6 cable, on the other hand, is pliable and is better suited for shorter distances. CAT 6 cable comes with a higher price tag than CAT 5/5e though the price is justified with better performance.