What documents will you refer to understand about features in the software?

In order to understand features and their functionality we refer requirement document (SRS). In order to understand overview of data flow, integration between systems, we should refer design document, For understanding documentation on code, algorithms, interfaces and APIs used in software technical documents or process documentation containing UML diagrams, How end user will use the software we can find from user manual, and finally how to install the software can be found from installation guide of the software.