What is "commercial off-the-shelf"

a. Systems which are manufactured commercially, and then tailored for specific uses.

Commercial off-the-shelf (COTS) is a term used to describe the purchase of products that are standard manufactured products rather than customized, or bespoke, products. A related term, Mil-COTS, refers to COTS products for use by the military.

In the context of US government, Federal Acquisition Regulation (FAR) has defined "COTS" as a formal term for commercial items, including services, available in the commercial marketplace that can be bought and used under government contract. For example, consumer goods and construction materials may qualify as COTS but bulk cargo does not. Services associated with the commercial items may also qualify as COTS, including installation services, training services, and cloud services.

COTS purchases are alternatives to custom developments or to one-off government-funded developments. A COTS product typically requires configuration that is tailored for specific uses, and the key characteristic that differentiates COTS from Custom software is that the user configurations are within the defined parameters of the commercial item and not the result of customizations to the commercial item itself. The use of COTS has been mandated across many government and business programs, as such products may offer significant savings in procurement, development, and maintenance.

Motivations for using COTS components include hopes for reduction of overall system-development and costs (as components can be bought or licensed instead of being developed from scratch) and reduced long-term maintenance costs. In the 1990s many regarded COTS as extremely effective in reducing cost and time in software development. COTS software came with many not-so-obvious tradeoffs—initial cost and development time can be reduced, but often with an increase in software component-integration work and also a dependency on the vendor, security issues and incompatibilities from future changes.