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I'm still confused as to the difference between FRCP 4 service and FRCP 5.

Is FRCP 5 for papers after the original pleading/summons is served?

This seems super basic, but it's stumped me forever.

The way my prof explained it is that Rule 4 is for service of process. Giving the defendant a summons and complaint to notify him he is being sued. It has more strict procedural requirements.

Rule 5 is for literally any other document. An amended pleading, a discovery request, etc. It has more liberal requirements (Example, they can be sent electronically)

Thank you!