Functional Testing:
Functional testing is defined as the process of ensuring that each feature of a software programme performs in line with the requirements and specifications. This type of testing does not concern the application's source code. The software programs various features are assessed by inputting test data anticipating the outcome and comparing the result with the expected one. This evaluation focuses on inspecting elements like user interface, APIs, database functionality, security measures, client or server applications and overall functionality of the Application Under Test. Functional testing can be carried out manually or, through automation. Helps determine the requirements of the systems software.

https://erpsolutions.oodles.io/developer-blogs/Black-Box-Testing/