When does "me-" go on verbs?
So I started learning Indonesian through a Duolingo course for 2 weeks now, and I've gotten to the "Me- Verbs" part as I'm writing this question.
I have already learned a few verbs from past lessons such as "makan" ("eat"), "minum" ("drink") and "pesan" (order), but what got me curious is that "memakan", "meminum" and "memesan" exists. They still mean the same word, but I don't get why "me-" is there in the first place.
Question: When does an existing verb use "me-" as a prefix if they can just not use it?