Sequence Diagrams

...or another article to address the problem of desperately searching for something because I can't recall how it's called 🤣

So I sometimes need to display a workflow or a chain of events in the software system (or any system or a set of), and then I remember that "there's this sthing with a parallel lines connected with arrows".

That thing is a Sequence Diagram, and, to quote the Wikipedia article,

It depicts the processes involved and the sequence of messages exchanged between the processes needed to carry out the functionality

There are various ways and tools to create one, and some more elaborate diagram tools have it in their arsenal - though I find this resource most convenient: https://sequencediagram.org/.

It lets to create the diagram with a sequence of simple command, adding entities automatically as they're mentioned in commands, e.g.

title Sequence Diagram Example UI->API:request user data API->DB:get data from DB DB->API:return data API->UI:return user structure

which displays

What's nice is this tool allows me to be as simple or as sophisticated as I want - there's a lot of bells and whistles available, such as various line types, notes, colors, icons, interactive elements and so on: https://sequencediagram.org/instructions.html.