Short Take-Off and Landing
A term used in the aircraft industry, to say that a plane is able to take-off and land at runways that are not (exceptionally) long. For example on an aircraft carrier, aircrafts that don't do STOL aren't of much use; they wouldn't be able to safely depart their ship.
Unless they would have VTOL capability of course, like the Harrier has, or helicopters.
Very often, a VTOL craft can also pull a STOL; then you would call it a V/STOL craft. Some helicopters are V/STOL capable - they do a short take-off when they are too heavily loaded for a vertical one. The above mentioned Harrier is another good example of V/STOL craft; yet another one is the V-22 Osprey.
To do a good STOL, the plane may not be too heavy, it needs a lot of thrust to get up to speed, and has got to have a lot of lift force. On an aircraft carrier, extra thrust is often provided by the catapult.
You get a lot of lift force by having well-designed wings (adjustable ones are the best: slim at high speed, and wide at take-off and landing.) An example of a plane with variable geometry wings that does short take-off (because it's being used on aircraft carriers) is the F-14 Tomcat.
Another way to get lift force is to use a tilt rotor design like the one used in the V-22 Osprey.
It's also possible to use the canard wings, if any, to get better STOL capabilities. They are normally used to prevent a stall, but not here. One would think that these mini-wings at the nose of the plane are just a good way to get extra lift. Not so.
The *do* give extra lift, but that doesn't make the plane take-off faster (the canards are too small for that.)
Instead, they only lift the nose of the plane. What's good about that, is that this changes the flying angle of the aircraft. In doing so, the engine gets directed more upwards (at first, it's completely horizontal.) So, instead of just pushing te plane forward, the engine now pushes it forward *and* upward. And off you go.
Note that there are better, more direct ways to alter the direction of a plane's thrust. Vectoring Thrust is a science on itself.