An inner tube is basically a doughnut-shaped balloon, with a valve for inflation. The only requirement for an inner tube is that it not leak. Being of rubber, it has no rigid structure. If an inner tube is inflated outside of a tire, it will expand to 2 or 3 times its nominal size, if it doesn't explode first. Without being surrounded by a tire, an inner tube can't withstand any significant air pressure.
Before World War II, tires and tubes were made from natural latex rubber, harvested from tropical trees. When the supply of natural latex was insecure during the war, a substitute, "butyl" was invented. Butyl turned out to be a very successful substitute, better, in fact, than latex for this application. All modern tires and most inner tubes use butyl rubber.
Some riders prefer latex inner tubes, because they can be a bit lighter than butyl ones. Some riders believe that latex tubes have less rolling resistance than butyl.
Latex tubes are commonly a bit more porous than butyl ones, and need to have their pressure topped off more often.