Generally, the offer is made as a consideration. The user deposits an X in cash and the house offers a corresponding percentage to play. This "money" can not, of course, be lifted; is an exclusive offer for the game. Suppose the casino offers 100% extra balance for deposits up to 100 euros. If you make a deposit of 50 euros, you will receive 100% of that amount as an extra balance, that is, another 50 euros. In practice, the player has paid 50 euros and will play 100.
Offers without deposit, also known as "free", are offered to the player without there being a prior obligation of deposit on his part. Registration offers generally assume this aspect, in which the user receives a value to play for the simple fact of registering on the site.
The online casino platforms of Portugal can also present other offers. There are rewards (between 5 to 10%, usually) for those who use certain means of payment to make deposits. They are an incentive to use electronic media, such as Paypal, Skrill or Neteller, for the advantages they offer both the casino and the user. And that, being recent, are still little used by most of the potential players.
For more frequent players or with the ability to invest more money, there are VIP offers. They may be granted particularly generous terms and generally involve personal and direct household contact - as expected from a true VIP treatment.
Welcome offers are especially important. As the name implies, new players are targeted by the casino, that is, new users who have just registered and create their player account on their platform. Often, those looking for a new casino to play will make their decision based on this initial offer.
A large part of the welcome "gifts" consists of a percentage offer related to the value of the first deposit. The more the player deposits for the first time in the casino, the greater the value of the offer. But they can take other forms, like free plays in slot machine games. Often, you can take both sides by combining a deposit offer with a certain number of free plays.
You need to be aware of the details of the offers. Free plays may only apply to some of the slot titles, not all. Welcome offers may also have specific lifting requirements; for example, the player may have to deposit a certain extra amount (in addition to what he has already deposited in order to be able to raise prizes obtained with the initial balance offered. It is always convenient to read carefully the Terms and Conditions, both the offer and the casino terms).