Bijections

A bijection is a special kind of relationship between two sets of objects where each element in the first set pairs with exactly one unique element in the second set, and vice versa. This means every element in both sets is connected in a one-to-one correspondence, with no leftovers. Think of it like matching pairs of gloves: every left glove has a matching right glove, and no glove is unmatched. Bijections are important because they show that two sets have the same size or number of elements, even if the objects themselves are different.