Category 6 cable, commonly referred to as Cat 6, is a cable standard for Gigabit Ethernet

Gigabit Ethernet

Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...

 and other network physical layer

Physical layer

The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....

s that is backward compatible with the Category 5/5e

Category 5 cable

Category 5 cable is a twisted pair cable for carrying signals. This type of cable is used in structured cabling for computer networks such as Ethernet. It is also used to carry other signals such as telephony and video. The cable is commonly connected using punch down blocks and modular connectors...

 and Category 3 cable

Category 3 cable

Category 3 cable, commonly known as Cat 3 or station wire, is an unshielded twisted pair cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz...

 standards. Compared with Cat 5 and Cat 5e, Cat 6 features more stringent specifications for crosstalk

Crosstalk (electronics)

In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel...

 and system noise. The cable standard provides performance of up to 250 MHz and is suitable for 10BASE-T

10BASE-T

Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. Other Ethernet cable standards employ coaxial cable or optical fiber. Early versions developed in the 1980s included StarLAN followed by 10BASE-T. By the 1990s, fast, inexpensive...

, 100BASE-TX (Fast Ethernet), 1000BASE-T/1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet).

Whereas Category 6 cable has a reduced maximum length when used for 10GBASE-T; Category 6a cable, or Augmented Category 6, is characterized to 500 MHz and has improved alien crosstalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols.
Like most earlier cables, Category 6 cable contains four twisted wire pairs

Twisted pair

Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...

.