How does a backend service validate an access token?

Thanks for the reply. Would these be the docs you were referring to? Auth0 Go API SDK Quickstarts: Authorization

It looks like I need to retrieve a public key from https://your_domain/.well-known/jwks.json in order to validate access tokens.

If I’m reading the docs correctly, then I need to know what “your_domain” is. Where is that domain name set? Is it set when I create the API application?