All Ethernet cables have four color-coded pairs of wires twisted together: green with green and white, brown with brown and white, and so forth. Ethernet cables and connectors are identified as Category 5 (CAT5), enhanced Category 5 (CAT5e), or Category 6 (CAT6), depending on the amount of data that can pass through a cable and the cable's sensitivity to interference. Unless you plan to install a super-fast Gigabit Ethernet network, CAT5e is usually the best compromise between cost and performance in a home or small office network.
Don't use CAT5 cable for new installations. It might be okay for today's networks, but it won't reliably support the next generation of high-speed data services.
Ethernet cables come in two forms: bulk cable on spools or in boxes, and pre-assembled cables with connectors already attached. Pre-assembled data cables are often called patch cords, patch cables, or jumper cables. They're available in many colors and in lengths ranging from 1 foot to 100 feet. Use different-colored patch cords with a switch or any other device that has lots of connections; multiple colors will allow you to find the right one quickly.
Bulk cable is the right choice for runs inside walls between your control center and the data outlets in other rooms. On the other hand, pre-built cables are better for shorter distances, such as between terminal blocks or wall outlets and computers, control devices, and other equipment, because they're often made with more durable jackets and plugs that have permanent collars. It's possible to build your own patch cords out of bulk cable and loose plugs, but attaching plugs to cables is tedious work that's generally more trouble than it's worth. As a rule of thumb, use bulk cable for permanent installations with a terminal block to each end, and pre-built cables for patch cords and for connections between wall outlets and network devices.
Patch cords are widely available in office supply and electronics stores, but they're often four or five times more expensive than the identical cables sold through industrial electronics suppliers and online sources such as Jameco (http://www.jameco.com/), Cyberguys (http://www.cyberguys.com/), and Newegg.com (http://www.newegg.com/). A 3-foot cable should not cost $8 or $10. There's no reason to pay more for "premium" patch cables; any cable that meets the CAT5e specification will do the job. (This piece of advice will probably save you more money than you paid for this book.)
In buildings with raised floors or dropped ceilings, it's often convenient to run your data cables through the plenum space above the ceiling or under the floor. However, fire regulations often require special plenum cable that won't burn easily and won't produce toxic fumes. Plenum cable is more expensive than regular bulk Ethernet cable, and it's more difficult to use because the jacket is heavier and less flexible, but there's no difference in its data-handling performance. When you're shopping for cable, you might find boxes or spools of plenum cable next to regular CAT5e cable. Sometimes the only difference is a single line on a label. Unless you have a specific need for plenum cable, don't waste your money on the more expensive stuff.