X.500

X.500 is a set of international standards for directory services that help organize and access network information, such as contact details of people, organizations, and resources. Think of it as a digital phone book for computer networks, allowing systems to locate and retrieve data efficiently. It uses a hierarchical structure similar to a family tree, making it easy to find information across large, complex networks. X.500 was widely adopted in the early days of networking to support directory services before more modern, internet-based solutions became common.