What is Ed25519 signature?

Can anyone tell me what an Ed25519 signature is?

I am seeing an error when I try to run through a loop making updates in my canister:

Body: Invalid signature: Invalid basic signature: Ed25519 signature could not be verified:

I believe this may have something to do with authentication timing out because if I decrease the number of times the loop has to be run, I appear to get this error less often. However, there seems to be no correlation between why sometimes it works and other times it doesn’t.

Any help with understanding this error message would be greatly appreciated.