How do television stations earn money?

Advertising. Companies pay -- often very handsomely -- for the privelage of getting their commercials on the air. Commercial spots vary in cost; the bigger the audience, the higher the cost. A 30-second ad space during the Superbowl now can cost more than a million dollars. With the advent of relaity shows, the networks make more money than ever. Reality shows don't carry the expense of locations, staff and casts that other shows do, so they're cheap to produce.