To hook up Hi Fi speakers to a receiver, we needed speaker wire. In the old days, we just used "lamp cord" -- the kind of two-conductor wire used to connect lamps to electrical sockets. Now there exist cables sold specifically for this application.
There is a lot of superstition sold with those cables and that increases the price. I wanted just reasonable cables, not high-markup ones such as you would find in Future Shop.
Canadian Tire sells packages RCA-brand speaker cable for about the same price as lamp cord. On advantage of the speaker cable is that it is designed so that you can tell one conductor from the other. This makes it easier to ensure that your speakers are not out of phase (i.e. the polarity of all speaker connections all match).
When looking at wire gauges, lower numbers are better. That means that there will be less signal loss, all other things being equal.