Newcomer to USA

what happen if immigration officer forgot to stamp on your passport? I mean to ask when you come from some other countries to USA and if they forget to stamp about Arrival date. In this case what we need to do? Is there any problem when you return to your native country?

do they stamp on you passport when you are going back? Because I have seen usally when we come from somewhere else to USA then tehy have to put stamp on your passport. I have seen first case when they forgot to put Arrival Stamp on Passport. I know they have all records when we came and when we are going back but I think this is for our reference that we need to know and we have to keep all the records for us.

so please if anyone know about it then please let me know. In this situation what we need to do?

Thanks and I hope I can know very soon from you.

Dilip.