Online casinos are offering free spins due to three reasons. The first one is obvious. They want to attract new players. The online gambling industry is known for tough competition, hence anything a casino can do to get an advantage over other casinos is a good thing. The second reason is to promote a game or a specific slot. This is the main reason all free spins deals are tied to a specific game. The third reason is the fact casinos will try to offer you other bonuses and promotions, and free spins are excellent, considering most players like slots.