An archivist is an information professional who assesses, collects, organizes, preserves, maintains control over, and provides access to records and archives determined to have long-term value. The records maintained by an archivist can consist of a variety of forms, including letters, diaries, logs, other personal documents, government documents, sound and/or picture recordings, digital files, or other physical objects.
As Richard Pearce-Moses wrote:
Archivists keep records that have enduring value as reliable memories of the past, and they help people find and understand the information they need in those records.
Determining what records have enduring value can be challenging. Archivists must also select records valuable enough to justify the costs of storage and preservation, plus the labor-intensive expenses of arrangement, description, and reference service. The theory and scholarly work underpinning archives practices is called archival science.
The most common related occupations are librarians, museum curators, and records managers. The occupation of archivist is distinct from that of librarian. The two occupations have separate courses of training, adhere to separate and distinct principles, and are represented by separate professional organizations. In general, the librarian tends to deal with published media (where the metadata, such as author, title, and date of publication, may be readily apparent and can be presented in standardized form), whereas the archivist deals with unpublished media (which has different challenges such as the metadata not always being immediately apparent, containing complications and variety, and more likely to depend on provenance). The Society of American Archivists (SAA) also notes that while both professions preserve, collect, and make materials accessible, librarians can often obtain "new copies of worn-out or lost books", while records in archival collections are unique and irreplaceable. The SAA further distinguishes libraries and archives based on the materials they keep and how they are accessed by patrons.