A private collection is a privately owned collection of works or valuable items. In a museum or art gallery context, the term signifies that a certain work is not owned by that institution, but is on loan from an individual or organization, either for temporary exhibition or for the long term. This source is usually an art collector, although it could also be a school, church, bank, or some other company or organization. By contrast, collectors of books, even if they collect for aesthetic reasons, are called bibliophiles, and their collections are typically referred to as libraries.

A work of art, artwork, art piece, piece of art or art object is an artistic creation of aesthetic value. Except for "work of art", which may be used of any work regarded as art in its widest sense, including works from literature and music, these terms apply principally to tangible, physical forms of visual art:An example of fine art, such as a painting or sculpture. Objects in the decorative arts or applied arts that have been designed for aesthetic appeal, as well as any functional purpose, such as a piece of jewellery, many ceramics and much folk art. An object created for principally or entirely functional, religious or other non-aesthetic reasons which has come to be appreciated as art. A non-ephemeral photograph or film. A work of installation art or conceptual art.