The Universal Decimal Classification (UDC) is a system used to organize library materials and information. It was developed in the late 19th century and is based on the Dewey Decimal Classification system. UDC uses a hierarchical structure, allowing for detailed categorization of subjects through a combination of numbers and symbols. UDC is widely used in libraries and information centers around the world, facilitating efficient information retrieval. It covers a broad range of topics, including science, technology, arts, and humanities, making it a versatile tool for organizing knowledge across various disciplines.