A shed is typically a simple, single-storey structure in a back garden

Back garden

A back garden is a residential garden located at the rear of a property, on the other side of the house from the public street-side entrance and front garden.-Number and size of back gardens:In Britain there are over 10 million back gardens....

 or on an allotment

Allotment (gardening)

An allotment garden, often called simply an allotment, is a plot of land made available for individual, non-professional gardening. Such plots are formed by subdividing a piece of land into a few or up to several hundreds of land parcels that are assigned to individuals or families...

 that is used for storage, hobbies

Hobby

A hobby is a regular activity or interest that is undertaken for pleasure, typically done during one's leisure time.- Etymology :A hobby horse is a wooden or wickerwork toy made to be ridden just like a real horse...

, or as a workshop

Workshop

A workshop is a room or building which provides both the area and tools that may be required for the manufacture or repair of manufactured goods...

.

Sheds vary considerably in the complexity of their construction and their size, from small open-sided tin-roofed structures to large wood-framed sheds with shingled roofs, windows, and electrical outlets. Sheds used on farm

Farm

A farm is an area of land, or, for aquaculture, lake, river or sea, including various structures, devoted primarily to the practice of producing and managing food , fibres and, increasingly, fuel. It is the basic production facility in food production. Farms may be owned and operated by a single...

s or in industry can be large structures.
The simplest and least expensive sheds are available in kit form.