> For the complete documentation index, see [llms.txt](https://ultimatewebsolutions.gitbook.io/qa-knowledge-base/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ultimatewebsolutions.gitbook.io/qa-knowledge-base/test-types/non-functional-testing.md).

# Non-functional testing

Checks **how well the system works** rather than what it does.

Examples:

* Performance testing
* Load testing
* Stress testing
* Security testing
* Usability testing
* Compatibility testing
* Reliability testing
* Scalability testing
* Accessibility testing

Example:

> "Can 10,000 users log in at the same time without the application becoming too slow?"