What situation are each pipeline status possible

Describe your question in as much detail as possible:
I know pipeline can take the following status:
created , waiting_for_resource , preparing , pending , running , success , failed , canceled , skipped , manual , scheduled
from this page: Pipelines API | GitLab

But I really want to know, what situation are each pipeline status possible?
I have seen status running , success , failed , canceled, but I have never seen other statuses.

Thank you for your help.