Component based software development (CBSD) focuses on building large software systems by integrating previously existing software components. By enhancing the flexibility and maintainability of systems, this approach can potentially be used to reduce software development costs, assemble systems rapidly, and reduce the spiraling maintenance burden associated with the support and upgrade of large systems. At the foundation of this approach is the assumption that certain parts of large software systems reappear with sufficient regularity that common parts should be written once, rather than many times, and that common systems should be assembled through reuse rather than rewritten over and over.

Component-based systems encompass both commercial-off-the-shelf (COTS) products and components acquired through other means, such as non-developmental items (NDIs).