Is ERC-20 the mainnet?

Excuse me, I'm trying to understand the intricacies of cryptocurrency technology, and I've come across the term ERC-20. I'm just a bit confused about its role and function. Could you please clarify if ERC-20 is considered the mainnet? I've heard people mention it in the context of Ethereum tokens, but I'm not sure if it's synonymous with the main blockchain network itself. It would be helpful if you could explain the difference between ERC-20 and a mainnet, and how they interact with each other, if at all. Your insights would greatly assist me in grasping this complex yet fascinating field.