Most routers and network cards don’t come with cables, so you must buy one for each PC. Network cables are sometimes flat, sometimes tube-shaped, but they all end with a plug slightly thicker than a phone plug. It’s officially called an RJ-45 connector.

If you’ll be running cable outdoors, over the roof, or any place exposed to sunlight, buy cables created specifically for outdoor exposure. Sunlight eats away at the plastic covering on the indoor cables.

For indoor cables, you may be struck with the wild idea of running Ethernet cables from room to room through your home’s heating or cooling ducts. Although it’s certainly been done, make sure to buy fire-resistant cable. Regular cable can catch fire, spreading the flames quickly to other rooms. Fire-resistant cable’s easy to find and many local safety codes require it for work environments.