Question about luggage on connecting flights

Hello!

I have a trip planned in May of this year, using American airlines (clearly, lol) and had a question.

When it comes to flights with what feels like a moderately long layover of 3 hours, what do I need to do with my luggage?

I am basically a first time flyer (the only other flight I took was ~30 mins, twelve years ago or so) and a first time international flyer.

Does the flight being international change what happens? I saw someone else asked the question and were told that it'd just be sent through, but I am still very anxious and wanted to make sure.