Non-functional testing is a type of software testing that evaluates the performance, usability, reliability, and other attributes of a system, rather than its functional behavior. Unlike functional testing, which focuses on verifying that the software functions correctly according to its specifications, non-functional testing aims to assess how well the software performs under different conditions and scenarios.

Non-functional testing encompasses various aspects of software quality, including:

Performance Testing: Evaluates the responsiveness, scalability, and stability of the system under different load conditions, such as high user traffic or heavy data volumes.

Usability Testing: Assesses the ease of use, intuitiveness, and user-friendliness of the system, including its interface design, navigation flow, and accessibility features.

Reliability Testing: Tests the system's ability to perform consistently and reliably over time, including its resilience to failures, errors, and disruptions.

Security Testing: Identifies vulnerabilities, risks, and threats to the system's security, including potential breaches, data leaks, and unauthorized access.

Compatibility Testing: Ensures that the software functions correctly across different devices, platforms, browsers, and environments, including hardware configurations and software dependencies.

Compliance Testing: Verifies that the software complies with relevant industry standards, regulations, and guidelines, such as GDPR, HIPAA, or PCI DSS.

Non-functional testing is essential for ensuring that the software meets performance objectives, user expectations, and business requirements, ultimately delivering a high-quality user experience and maintaining the system's integrity, reliability, and security.