A stable set, also known as a stable matching or independent set, is a concept in graph theory. It refers to a subset of vertices in a graph where no two vertices in the subset are adjacent. This means that there are no direct connections between any of the selected vertices, ensuring that they can coexist without conflict. In practical applications, stable sets are used in various fields, including computer science and economics. They help in solving problems related to resource allocation, scheduling, and network design, where it is essential to select non-conflicting options from a larger set.