Functional testing is an example of black-box dynamic testing. Functional testing is the process of testing the functionality or behavior of a software system based on its requirements or specifications. Functional testing does not require any knowledge of the internal structure or implementation of the system under test; it only focuses on what the system does rather than how it does it. Functional testing is also an example of dynamic testing because it involves executing the software system with selected inputs and observing its outputs and effects on the environment. Dynamic testing is different from static testing, which involves examining the software system without executing it, such as code inspection, static analysis, etc. You can find more information about functional testing and dynamic testing in A Study Guide to the ISTQB® Foundation Level 2018 Syllabus, Chapter 21.