An event triggers a workflow, each workflow needs to have at least one job. Each job has one or multiple steps.
A step can be either and action (not the same as a GitHub action) or a shell command.
Each job is related to one runner (e.g. different jobs run on different runners)
Steps cannot run in parallel.
GitHub hosted runners come in Ubuntu, Windows, or Mac
GitHub actions are stored in the root dir (don't know whether that is mandatory) in the .github folder.
Workflows need to be saved under .github/workflows
Find publicly available GitHub Actions