A reference collection is a collection

Collecting

The hobby of collecting includes seeking, locating, acquiring, organizing, cataloging, displaying, storing, and maintaining whatever items are of interest to the individual collector. Some collectors are generalists, accumulating merchandise, or stamps from all countries of the world...

 of objects maintained for the purpose of study and authentication. Reference collections are generally large undertakings maintained by institutions; instead of having a single representative of each object, they will typically have multiples, so as to illustrate variations and, sometimes, provide samples for comparisons. For human-created objects such as postage stamp

Postage stamp

A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are made from special paper, with a national designation and denomination on the face, and a gum adhesive on the reverse side...

s or coin

Coin

A coin is a piece of hard material that is standardized in weight, is produced in large quantities in order to facilitate trade, and primarily can be used as a legal tender token for commerce in the designated country, region, or territory....

s, a good reference collection will also include an assortment of (carefully labelled) fakes and forgeries.

Since the purpose is study rather than personal gratification or display, a reference collection values damaged objects as much as the pristine; in fact, organizations maintaining reference collections will encourage members to donate their damaged or poor-condition items to the collection.

In biology

Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, reference collections, such as herbaria

Herbarium

In botany, a herbarium – sometimes known by the Anglicized term herbar – is a collection of preserved plant specimens. These specimens may be whole plants or plant parts: these will usually be in a dried form, mounted on a sheet, but depending upon the material may also be kept in...

 are an important sort of information about variations of populations within a species. They are also the repository of holotype

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

s used as the official definition of species.

In philately

Philately

Philately is the study of stamps and postal history and other related items. Philately involves more than just stamp collecting, which does not necessarily involve the study of stamps. It is possible to be a philatelist without owning any stamps...

, reference collections are critical to expertization

Expertization

Expertization is the process of authentication of an object, usually of a sort that is collected, by an individual expert or a committee of experts.The expert committee will examine the collectible and issue a certificate typically including:...

, since the characteristics differentiating authentic stamps from reprints, fakes, and forgeries are often too subtle to be described verbally.