Free spins can be offered for a variety of reasons. You may be able to claim a free spin bundle by registering an account, or you may receive free spins as part of your deposit-based welcome package. Some casinos allocate the spins automatically once you have performed the qualifying action (eg. registered an account or made a deposit), while others may require a bonus code to release the spins. Each casino's requirements will vary, so do check the terms and conditions.