Some deposits of natural gas are easier to tap than others. Before the widespread use of fracking, drillers would limit their natural gas wells to deposits that lay in easily reached pools beneath the earth. How much natural gas they would tap from existing wells, and how extensively they searched for new deposits and drilled new wells, depended on the price they expected to get for the natural gas. The higher the price they expected, the more they would tap existing wells as well as drill and tap new wells.
The quantity supplied is the actual amount of a good or service people are willing to sell at some specific price.
So just as the quantity of natural gas that consumers want to buy depends upon the price they have to pay, the quantity that producers of natural gas, or of any good or service, are willing to produce and sell—