What is pairwise DID?

I am confused about what a pairwise DID is.

My thnk on pairwise DID are as follows.

Using identifiers such as cell phone numbers in multiple contexts risks tracking personal information.
So Identity Owner makes it impossible to associate with different DIDs for each context.

What I am wondering here is to generate multiple DIDs from one public key? Or are you generating multiple public keys and corresponding DIDs?

If it is the latter, what is the advantage of pairwise DID compared to the individual simply managing multiple public keys?

Please let me know if there is anything wrong with my explanation.

Thank you.