Definition of Pot Limit
"Pot Limit" means that the variant of poker in question does not allow, as in the variants of poker without limits, to put all its carpet in play at any time. Therefore, there are betting limits that are calculated relative to the size of the pot. For example, in the No Limit Hold’em, if you have a €100 stack, you can bet it on flop, even if the pot in flop is €10. In no-limit variations, it is the size of your stack that will determine your maximum bet, not the size of the pot. In a "Pot Limit" variation, you would not be able to bet more than $10. The poker Pot Limit type is most popular in the Omaha.
Why is Pot Limit Omaha the most popular bet type?
If you see a poker variant that is a "Pot Limit", chances are it will be an Omaha. The reason being that in Omaha, the preflop hands are closer together than in Hold'em. While you can have a huge advantage between two hands at Hold’em (an 80%/poker% for example), this is never the case at Omaha. The big equity gaps between two hands will be more like 65%/35%. For this reason, a limit is imposed on each bet.