Events can be used to invoke your Forge app without an UI interaction, for example:
Jira,
Confluence,
Compass,
Bitbucket (EAP) and
Life cycle events are
generated by user activity in the products. Your app can subscribe to
one or more events via the manifest.yml file.
Web trigger events are
incoming HTTP requests. You can supply these web trigger URLs to invoke
your app from a third-party app.
You can also use scheduled triggers
to invoke your app on a periodic basis.