An exhibition, in the most general sense, is an organized presentation and display of a selection of items. In practice, exhibitions usually occur within museums, galleries and exhibition halls, and World's Fairs. Exhibitions include [whatever as in major art museums and small art galleries; interpretive exhibitions, as at natural history museums and history museums], for example; and commercial exhibitions, or trade fairs
The word "exhibition" is usually, but not always, the word used for a collection of items. Sometimes "exhibit" is synonymous with "exhibition", but "exhibit" generally refers to a single item being exhibited within an exhibition
Exhibitions may be permanent displays or temporary, but in common usage, "exhibitions" are considered temporary and usually scheduled to open and close on specific dates. While many exhibitions are shown in just one venue, some exhibitions are shown in multiple locations and are called travelling exhibitions, and some are online exhibitions
Though exhibitions are common events, the concept of an exhibition is quite wide and encompasses many variables. Exhibitions range from an extraordinarily large event such as a World's Fair exposition to small one-artist solo shows or a display of just one item. Curators are sometimes involved as the people who select the items in an exhibition. Writers and editors are sometimes needed to write text, labels and accompanying printed material such as catalogs and books. Architects, exhibition designers, graphic designers and other designers may be needed to shape the exhibition space and give form to the editorial content. Exhibition also means a scholarship.
Art exhibitions 
Art exhibitions include an array of artifacts from countless forms of human making: paintings, drawings, crafts, sculpture, video installations, sound installations, performances, interactive art, etc. Art exhibitions may focus on one artist, one group, one genre, one theme or one collection; or may be organized by curators, selected by juries, or show any artwork submitted.
Fine arts exhibitions typically highlight works of art with generous space and lighting, supplying information through labels or audioguides designed to be unobtrusive to the art itself.
Exhibitions may occur in series or periodically, as in the case with Biennales, triennials and quadrennials.
Interpretive exhibitions 
Interpretive exhibitions are exhibitions that require more context to explain the items being displayed. This is generally true of exhibitions devoted to scientific and historical themes, where text, dioramas, charts, maps and interactive displays may provide necessary explanation of background and concepts. Interpretive exhibitions generally require more text and more graphics than fine art exhibitions do.
The topics of interpretive graphics cover a wide range including archaeology, anthropology, ethnology, history, science, technology and natural history. Examples of such exhibitions may be found at the Natural History Museum, museums of the Smithsonian Institution, the American Museum of Natural History and the Field Museum — to name a few of the largest museums of this kind.
Commercial exhibitions 
Commercial exhibitions, generally called trade fairs, trade shows or expos, are usually organized so that organizations in a specific interest or industry can showcase and demonstrate their latest products, service, study activities of rivals and examine recent trends and opportunities. Some trade fairs are open to the public, while others can only be attended by company representatives (members of the trade) and members of the press.
Exhibitions as marketing tools 
Throughout the ages, trade fairs have been recognized as one of the most efficient and powerful tools for effectively doing business. As a face-to-face meeting point, fairs and exhibitions are basically a target opportunity for achieving your trade objectives. They are a cost-effective means to reach your market audience - in one time and in one place. Among the key advantages of trade show participation is:
Customer contact: Trade shows provide excellent venues for initiating contacts with new customers and developing new trade leads. Equally important they enable you to maintain and renew contacts with valued clients.
Product and Service Launch Platforms: Live presentations and Demonstrations of your products and services speak for themselves, accelerating the selling process and generating new sales.
Marketing Communications: Trade fairs focus media attention on your Company and products. Public relations efforts can be focused to raise the profile of your company image and brands.
A high return/expense ratio: Trade shows are known to have a high return/expense ratio. An EEAA (Exhibition Association of Australia) survey showed that an average expenditure of 9% of companies' marketing budgets in trade far events resulted in a return of 23% of business.
CEIR (centre of exhibition industry researches): - 76% of exhibition attendees arrive with an agenda; - 48% of exhibition leads don't require a sales call to close the deal; - Exhibition leads cost 56% less to close than field sales calls; - 87% of exhibition attendees say they will share information obtained at exhibitions with their immediate superiors.