A museum is a building or institution that cares for and displays a collection of artifacts and other objects of artistic, cultural, historical, or scientific importance. Many public museums make these items available for public viewing through displays that may be permanent or temporary. The largest museums are located in major cities throughout the world, while thousands of local museums exist in smaller cities, towns, and rural areas. Museums have varying aims, ranging from the conservation and documentation of their collection, serving researchers and specialists, to catering to the general public. The goal of serving researchers is not only scientific, but intended to serve the general public.

There are many types of museums, including art museums, natural history museums, science museums, local history museums, and children's museums. According to the International Council of Museums (ICOM), there are more than 55,000 museums in 202 countries.

The purpose of modern museums is to collect, preserve, interpret, and display objects of artistic, cultural, or scientific significance for the study and education of the public. From a visitor or community perspective, this purpose can also depend on one's point of view. A trip to a local history museum or large city art museum can be an entertaining and enlightening way to spend the day. To city leaders, an active museum community can be seen as a gauge of the cultural or economic health of a city, and a way to increase the sophistication of its inhabitants. To a museum professional, a museum might be seen as a way to educate the public about the museum's mission, such as civil rights or environmentalism. Museums are, above all, storehouses of knowledge. In 1829, James Smithson's bequest, that would fund the Smithsonian Institution, stated he wanted to establish an institution for the increase and diffusion of knowledge.