Sequence diagram is a very useful tool for representing a sequence of interactions between objects, modules or processes. I am using it mostly to represent HTTP interactions between REST APIs or Web Services. It’s very easy to understand within your team and with your stakeholders. There are many good books about Unified modeling language UML, but you can start your UML journey here.
The syntax is simple and you can be generating sequence diagrams in no time! Check out the documentation page for more information and try it out.