Cardinality refers to the concept of the size or number of elements in a set. In mathematics, it helps to compare the sizes of different sets, determining whether they are finite, countably infinite, or uncountably infinite. For example, the set of natural numbers has a cardinality denoted as ℵ₀, indicating it is countably infinite. Understanding cardinality is crucial in various fields, including computer science and statistics. It allows for the classification of sets and the exploration of their properties. The distinction between different types of infinity, such as the cardinality of real numbers versus natural numbers, is a fundamental aspect of set theory.