As the use of digital computers escalated over the past forty years the financial costs of software failure increased correspondingly, and the importance of software testing grew.
Software development and validation are simultaneous processes. The processes of software testing start at the birth of the product and go on during the whole of its construction. Verification and validation are difficult because a developer cannot test the software forever and it is hard to estimate how much evidence is sufficient.
When applied to a computer system, validation, as defined by the FDA, can be interpreted as documented evidence, which provides a high degree of assurance that a computer system performs its intended functions accurately and reliably.1