Cat5, Cat5e, Cat6… what does it all mean? They’re categories of twisted-pair Ethernet cable, of course, but all twisted-pair Ethernet cables are not created equal. These Cats are all part of one big happy family of copper cabling standards defined jointly by the Electronic Industries Alliance and the Telecommunications Industry Association, and defined in TIA/EIA-568. Let’s take a look at the characteristics of each.

Pre-Cat5

The twisted-pair cable was invented by Alexander Graham Bell. You might have heard of him; he also invented the telecommunications industry. That’s not particularly relevant to this topic, but it is a neat bit of trivia, isn’t it? In any case, Category 3, commonly used in the early 1990s, was the first Ethernet cable. It’s still used for telephones, but with a top speed of 10 Mbps, that’s about all it’s still good for. Cat4 had its own brief heyday, but was superseded by Cat5 and is not recognized by the current version of TIA/EIA-568.

Cat5

Introduced around 2000, Cat5 uses either the 10BASE-T or 100BASE-T standard for data transmission and is rated for a maximum frequency of 100 MHz and top speeds of 100 Mbps. While it is still commonly used for local area networks, it is too slow for most other applications, and is arguably on its way to obsolescence.

Cat5e

Kind of like Cat5, but enhanced. (That’s what the “e” stands for.) Cat5e was designed to reduce crosstalk and generally speed stuff up. At the same bandwidth as its immediate predecessor (100 MHz, remember?), it can handle speeds up to 1,000 Mbps. Woo-hoo! Gigabit Ethernet! (Your mileage may vary.)

Cat6

At 250 MHz, Category 6 cable has more than double the bandwidth of Cat5, and is suitable for up to 10-gigabit Ethernet. While that might seem like overkill, when you consider that the “digital universe” is projected to double every two years between now and 2020, all that bandwidth starts to sound like a good way to “future-proof” a residential or commercial network. Cat6 also has an improved signal-to-noise ratio.

Cat6a

With the max frequency jacked to 500 MHz and even less cross-talk, the “a” presumably stands for “awesomer”.

Cat7 and more

What does the future hold? As a wise philosopher once proclaimed, “To infinity…and beyond!” Although it’s not recognized by TIA/EIA, Category 7 cable is out there. In Cat7, each of the twisted pairs is fully shielded, which eliminates alien crosstalk almost completely and significantly improves noise resistance. And then there’s Category 8, projected to be specified to 2 GHz…but that one’s still under development.

So, that’s your quick crash course in copper-cable categories. (Say that three times fast.) Which category you choose for your residential or commercial network will depend on your need for speed. Just keep in mind the oft-repeated truism that any network is only as fast as its slowest component, which means that all your cables and routers will have to support Gigabit Ethernet if you want to reach those speeds.