A Hasse diagram is a graphical representation of a partially ordered set, illustrating the relationships between its elements. In this diagram, elements are represented as points, and lines connect them to show the order relation, with higher elements placed above lower ones. The absence of lines indicates that there is no direct relationship between those elements. Hasse diagrams are commonly used in various fields, including mathematics and computer science, to visualize order relations such as subsets or divisibility. They help in understanding concepts related to lattices, posets, and order theory by providing a clear and concise way to depict complex relationships.