Software validation is the systematic process of evaluating software throughout its development lifecycle to ascertain that it satisfies specified requirements and fulfills its intended purpose for the user. It investigates the degree to which the software meets user needs in its operational environment, focusing on the external behavior and functionality from the user's perspective. Key characteristics include its emphasis on ensuring the system 'does the right thing,' often contrasting with verification, which ensures the system 'is built right.' The significance of software validation lies in assuring the fitness for purpose, reliability, and safety of software systems, particularly in critical applications, thereby enhancing user confidence and mitigating operational risks.