Contractors are organizations that carry out construction works, that is, any building, civil engineering or engineering construction work.

A contractor is a person or company that works on a contractual basis, negotiating deals with different clients to work on specific jobs or projects.

Within this very broad definition, there are a very wide range of different types of contractor:

Approved contractor
A contractor that has demonstrated they have the expertise, resources, ability and desire to tender for a proposed project.

Construction manager
A construction manager does not undertake the construction works themselves, but manages trade contractors to carry out the works. The trade contracts are placed with the client.

Design, build and manage contractor
A contractor that is appointed not only to design and build the works, but also to manage them during operation, sometimes providing operational services over and above building maintenance, such as supplying operational staff, cleaning and so on.

General contractor, prime contractor or main contractor
A contractor who undertakes the entire construction of a project, but who will usually sub-let parts of the works to subcontractors.
The term ‘prime contractor’ is often used in central civil government and the defense sector to mean ‘main contractor’, although it can also have a different meaning.