What is the primary purpose of software testing?

The primary purpose of software testing is to evaluate functionality, performance, and security of applications. This process is essential in ensuring that the software meets specified requirements and performs its intended functions correctly under various conditions. Testing helps identify bugs or errors before the software is deployed, significantly reducing the risk of failures in a live environment.

Through testing, developers can verify that features work as expected, assess how the software handles load and stress, and ensure that it protects against vulnerabilities. By focusing on these critical aspects, software testing thereby contributes to the overall quality and reliability of applications, which is vital for user satisfaction and business success.

Other options do not capture the comprehensive aim of testing; while improving aesthetics and user training are important, they are secondary to the fundamental goal of verifying that the software operates effectively and securely. Reducing file size could enhance performance but isn't a direct objective of testing itself.