What are the Pre-job and Post-job tasks appearing in Azure DevOps Pipeline Logs

My Pipeline tasks are as follows: (key one is Signing and aligning APK file(s) one).

When I am looking at logs of the build(s), apart from the Signing and aligning APK file(s) task logs there I also see Pre-job: Signing and aligning APK file(s) one and Post-job: ... ones (same as for Checkout).

However, I don't quite understand what those tasks are and how it appeared I have them in logs? I can't find any documentation related to that. And, correspondingly, considering there are the "Pre-job" tasks if there is any way to define my own tasks executing before the Pipeline build starts?

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