Many online casinos offer free spins or free slots to play. The idea behind this is that the player can try the kind of online slots game he or she is interested in for free and then they can become real players and will play for real.
This practice is common these days in online gambling and is a gold opportunity to attract visitors that finally might convert into real casino players.
All players are different - you cannot make all of them happy. Once you have attractive bonuses like welcome, signup bonus or a lavish match bonus people will flock to your online casino site through google or affiliates.
Online casino slots are by far the type of online casino games that attract visitor and players. And there is plenty of them from different casino software providers like Microgaming, RTG or Rival just to name a few.
Also - promotions are based on special bonuses or new slot game features - this is what most players are looking for.
So offering the best casino bonus or free casino slot games is a good way of letting people know that you have come up with something new that might be of interest to them.