Archivists contribute to the study of the arts and sciences by analyzing, acquiring, and preserving historical documents, artwork, organizational and personal records, and information systems that are significant enough to be preserved for future generations. Archivists keep track of artifacts such as letters, contracts, films, photographs, video and sound recordings, digital files, blueprints, and other items of potential historical significance. Approximately 5,560 archivists are employed in the United States.