Turn-key

A turnkey or a turnkey project (also spelled turn-key) is a type of project that is constructed so that it can be sold to any buyer as a completed product. This is contrasted with build to order, where the constructor builds an item to the buyer's exact specifications, or when an incomplete product is sold with the assumption that the buyer would complete it.

A turnkey project or contract as described by Duncan Wallace (1984) is:

…. a contract where the essential design emanates from, or is supplied by, the Contractor and not the owner, so that the legal responsibility for the design, suitability and performance of the work after completion will be made to rest … with the contractor …. 'Turnkey' is treated as merely signifying the design responsibility as the contractor's.

A turnkey computer system is a complete computer including hardware, operating system and application(s) designed and sold to satisfy specific business requirements.

Turnkey refers to something that is ready for immediate use, generally used in the sale or supply of goods or services. The word is a reference to the fact that the customer, upon receiving the product, just needs to turn the ignition key to make it operational, or that the key just needs to be turned over to the customer. Turnkey is often used to describe a home built on the developer's land with the developer's financing ready for the customer to move in. If a contractor builds a "turnkey home" they frame the structure and finish the interior. Everything is completed down to the cabinets and carpet. "Turnkey" is commonly used in the construction industry, for instance, in which it refers to the bundling of materials and labour by Home Builder or General Contractor to move into the home without owner involvement. 'Turnkey' is also commonly used in motorsports to describe a car being sold with drivetrain (engine, transmission, etc.) to contrast with a vehicle sold without one so that other components may be re-used.

Similarly, this term may be used to advertise the sale of an established business, including all the equipment necessary to run it, or by a business-to-business supplier providing complete packages for business start-up. An example would be the creation of a "turnkey hospital" which would be building a complete medical centre with installed medical equipment.

The term turnkey is also often used in the technology industry, most commonly to describe pre-built computer "packages" in which everything needed to perform a certain type of task (e.g. audio editing) is put together by the supplier and sold as a bundle. This often includes a computer with pre-installed software, various types of hardware, and accessories. Such packages are commonly called appliances. A website with a ready-made solutions and some configurations is called a turnkey website.

...
Wikipedia