Closed Sets

A closed set is a concept from mathematics, specifically in topology and analysis. It includes all its boundary points, meaning if a point is just at the edge of the set, it’s still part of it. For example, the set of all points on and inside a circle is closed because it contains every point on the circle's boundary. Conversely, an open set might include points inside but not on the boundary. Closed sets are important because they help describe shapes and spaces where limits and boundaries are well-defined, providing structure in mathematical analysis.