Multi-Flights Effective stack size is the size of the smallest stack between two different players in a hand. Knowing effective stack sizes is an essential concept in basic poker strategy — how we earn money playing poker online play a particular hand will vary greatly depending upon our opponents’ stack sizes. You've already come across some poker jargon in the Beginner's articles. You will continue to hear terms like, "set" and "trips" in other articles, coaching videos and in the forums. You don't need to learn them all by heart in order to take part in the strategy discussions, since you can look them up in the PokerStrategy.com glossary, but knowing some of the common terms will help you understand the strategy articles and videos, as well as the forum discussions, more easily.