Collection (artwork)

A museum is distinguished by a collection of often unique objects that forms the core of its activities for exhibitions, education, research, etc. This differentiates it from an archive or library, where the contents may be more paper-based, replaceable and less exhibition oriented, or a private collection of art formed by an individual, family or institution that may grant no public access. A museum normally has a collecting policy for new acquisitions, so only objects in certain categories and of a certain quality are accepted into the collection. The process by which an object is formally included in the collection is called accessioning and each object is given a unique accession number.

Museum collections, and archives in general, are normally catalogued in a collection catalogue, traditionally in a card index, but nowadays in a computerized database. Transferring collection catalogues onto computer-based media is a major undertaking for most museums. All new acquisitions are normally catalogued on a computer in modern museums, but there is typically a backlog of old catalogue entries to be computerized as time and funding allows.

Museum collections are widely varied. There are collections of art, of scientific specimens, of historic objects, of living zoological specimens and much more. Because there are so many things to collect, most museums have a specific area of specialization. For example, a history museum may only collect objects relevant to a particular county or even a single person, or focus on a type of object such as automobiles or stamps. Art museums may focus on a period, such as modern art, or a region. Very large museums will often have many subcollections, each with its own criteria for collecting. A natural history museum, for example, will have mammals in a separate collection from insects.

Because museums cannot collect everything, each potential new addition must be carefully considered as to its appropriateness for a given museum's defined area of interest.