What is the difference between negative and not detected in STD?

In STD testing, "negative" typically means that the test did not find evidence of the specific infection being tested for, indicating that the individual is likely free of that STD. On the other hand, "not detected" often refers to tests that look for the presence of the infection's genetic material or antigens, suggesting that the pathogen was not present in the sample collected. While both terms indicate an absence of infection, "not detected" may imply that the test was performed but did not find any indicators of the disease, which can be relevant for tests with varying sensitivity.