The welcome bonus is used as both a sign-up bonus and someti me s its the name for the deposit bonus. What’s common in both cases is that you need to be a new registered customer to have the right to get the bonus.
The welcome bonus is either free money or free spins and always comes with terms and conditions. These can be winning cap or wagering requirements. It’s also pretty standard that the bonus credit only can be used at specific slot machine games.