Rara (from Latin rarus = rare, singular) is a term used in libraries for particularly valuable illuminated manuscripts, old prints or special documents and writings that are cataloged and stored separately, often in specially secured and ventilated vaults.

Due to their uniqueness and preciousness, such collections are usually only presented to the user on request and in separate reading rooms. In the past, alternatives were facsimile editions or microfilming.

Thanks to the development of gentle, conservative book scanners, these holdings are now increasingly available both to scholar and a broader public worldwide as digital copies.