How does a glider become airborne?

During World War 2, most military gliders were pulled into the air and to their point of release by another powered airplane. Modern sports gliders also use this method. The Wright Brothers launched their glider using a Tower and a falling weight. I think I have read about early "barn stormers' in the 1930's who launched aircraft with something like a bungee rope. There there is the easy way; push the glider down a steep hill that has a wind blowing into the glider.