Cat 5 cables are often used in structured cabling for computer networks such as Fast Ethernet, although they are also used to carry many other signals such as basic voice services, token ring, and ATM (at up to 155 Mbit/s, over short distances).

Cat 5e cable is an enhanced version of Cat 5 for use with 1000BASE-T (gigabit) networks, or for long-distance 100BASE-TX links (350 ft, compared with 100 m for Cat 5). It must meet the EIA/TIA 568A-5 specification. Virtually all cables sold as Cat 5 are actually Cat 5e. The markings on the cable itself reveal the exact type.

Straight-through Cat 5 cables are used to connect a computer to a hub or a switch. Straight-through cables are used to connect different OSI layer devices. Straight through cables are also used by some phone systems and Token Rings. Although the TIA-568A standard is preferred for new installations, it makes no difference which is used.

Crossover Cat 5 cables are used to connect PC-to-PC, hub-to-hub, switch-to-switch, etc. Crossover cables are used basically to connect devices of the same OSI layer. The general rule of thumb is that if two devices of the same type are to be connected, a crossover cable is used. To make a crossover cable, one end should use the TIA-568A standard and the other end should use the TIA-568B standard. What this does is effectively hard-wire the transmit module of each device to the receive module of the other.

Roll-over Cat 5 cables are used to connect a computer to the console port of a router. This type of cable is used while configuring enterprise routers. To make a roll-over cable, one end should use either the TIA-568A or the TIA-568B standard, while the other end should use the same standard but in reverse or "rolled over".

Other categories of network cables

• Cat 1: Used for telephone communications and not suitable for data transmission.
• Cat 2: 4 Mbit/s cables for low-speed data.
• Cat 3: 10 Mbit/s cables, a well-known variant of Cat 5 cables.
• Cat 4: 20 Mbit/s cables, being phased out in favor of Cat 5.
• Cat 6: defined by the ANSI TIA/EIA 568B-2.1. It is suitable for 1000 Base-T Ethernet up to 100 m.
• Cat 7: cable, with four individually-shielded pairs (ScTP) inside an overall shield, has been proposed as a standard but did not gain its popularity.