UTP cables use eight wires grouped in four pairs, each composed of a solid-colored wire and a stripped wire. Each wire is twisted a certain number of times to minimize interferences with the other pairs. A higher number of twists per inch results in higher data transmission. The Electronic Industry Association and Telecommunication Industry Association have established six-speed standards for UTP cables, with category 1 cables being the slowest and category 6 cables the fastest.

The category of a UTP cable has a high impact on its usage range. Category 1 cables have a speed of 1 Megabit per second, or Mbps, and can only be used in telephony. Category 2, 3, and 4 cables are used in telephony and low-speed networks; CAT 5 cables have a speed of 100 Mbps in a two-pair configuration, known as 100BaseT Ethernet, and 1,000 Mbps if all 4 pairs are used, such as in Gigabit Ethernet. Category 6 wires are capable of speeds up to 10,000 Mbps. Category 5 cables are the most used in regular networks, while category 6 cables are more specific to high-speed networks between servers