What is considered a successful death saving throw?

I’m fairly new to D&D and I wanted to run a session with some friends. I’ve been doing a lot of research but can’t seem to find an answer to this question. I understand how the mechanic works, three successes or rolling a 20 being stabilized and the opposite being death. However what I want to know is what would be considered a success? Is this up to the DM or is there a guide? I would assume anything above 10 would be a success and anything below would be a failure but I’d like clarity.