The advice above applies mainly to cables for indoors. However, if you’re going to run cables externally, it’s not a great idea to buy standard indoor Cat5, 6 or 7. Outdoor cable should have a PE coating which won’t degrade and turn brittle as standard PVC coatings will. Also, outdoor Ethernet cables have solid copper wires, not the multi-strand wires that indoor cables have.  This means outdoor network cabling isn’t as flexible, but it’s designed to be tougher and for those solid cores to be installed into Ethernet faceplates. And it’s a good idea to use faceplates instead of just attaching RJ-45 connectors to the ends. Faceplates are inexpensive and lend a much more professional finish. If you’re going to run the cable in the ground, then you’ll need ‘direct burial’ cable which is designed to withstand moisture. It’s also possible to buy shielded outdoor Ethernet cable which prevents interference.  Outdoor cable generally comes on reels from 20m up to 305m, and you’ll need a special ‘push-down’ tool to push the wires into the connectors on the faceplates. When choosing, watch out for cheaper ‘CCA’ cable – copper-coated aluminium. This will not carry power, so is no use for conntecting CCTV or PoE (power-over-ethernet) devices. In the UK, Kenable is one of the best places to buy outdoor cabling, along with faceplates and any tools you might need.