How do video game season passes actually work?

I'm thinking of purchasing the Saint's row 3 season pass. and I have no clue how it works exactly some places say that if i buy the pass I get the three dlc free. Others say it's just a discount. any one bought one for Mortal kombat or the one for gears? how exactly do they work. ThanksHow do video game season passes actually work?
The Season Pass is like pre-paying for DLC. By buying the pass, you don't have to buy the individual DLC packs that the pass includes, and you usually get a discount for buying it all at once.



For example, the Saints Row Season Pass is $20. It includes 3 DLC packs that would probably cost $10 each. So, you're spending $20 now before the packs come out, instead of $30 if you bought each DLC as they came out -- a $10 discount.