Sometimes you have a set of items (could be numbers, names, custom entities, .....) and you need to get all possible combinations each consists of a given number of items from the bigger set. Imagine that you need to write a program by which a user can define some birthday gifts. Each gift has an id, name, description, price, ... Your program is expected to provide all possible combinations of gifts that a father can get to his son given that the number of gift items doesn't exceed 5 and the price doesn't exceed LE 150. The "Items Combinations Generation Library" library provides a class with some methods which you can use to get all possible combinations of any set of items. If you want to know more, you can read this article.