Free spins are a type of promotional offer that you can get when playing at an online casino. Simply put, you get a certain number of attempts in advance that can be used on a particular slot machine. They come in the form of no-deposit bonuses or as part of deposit bonus packages.

Deposit Bonuses: The most common variety of online casino bonus is the deposit bonus or match bonus. It is given away as a percentage of players' deposit amounts. For example, a 100% match or deposit bonus of up to $100 means that the deposit amounts of a player will be doubled to a maximum of $100.