Aleph Null, often represented as ℵ₀, is a concept in mathematics that denotes the smallest type of infinity. It is used to describe the size of countably infinite sets, such as the set of natural numbers 0, 1, 2, 3, .... This means that even though there are infinitely many natural numbers, they can be listed in a sequence. In contrast to larger infinities, Aleph Null helps mathematicians understand different levels of infinity. For example, the set of real numbers is uncountably infinite and is represented by a larger infinity, often denoted as ℵ₁. This distinction is crucial in set theory, a branch of mathematical logic.