For deployment automation, it is convenient to have an action that can trigger a workflow in another repository by creating a repository dispatch event using the github API.
This is similar to a webhook, but gives us control over the event content.
(Moreover, I wouldn't know how to authenticate to the target repository with a webhook...)
Also see key-differences-between-reusable-workflows-and-composite-actions
For deployment automation, it is convenient to have an action that can trigger a workflow in another repository by creating a repository dispatch event using the github API.
This is similar to a webhook, but gives us control over the event content.
(Moreover, I wouldn't know how to authenticate to the target repository with a webhook...)
Also see key-differences-between-reusable-workflows-and-composite-actions