Github rest APIs authentication

Hi,
I am looking for Github rest apis and found the reference for these.
I have used a few API and it is working fine.
My doubt is when we have to use the authentication token with APIs ?.
What kind of APIs will need token authentication as the current one i have used does not require any token.
Kindly provide the information

Access to information that is not public will require authentication, as GitHub must check the requesting user has the necessary permissions to receive any information requested. Where tokens are used the scopes defined for the token must be sufficient also.

The documentation will also give an indication of whether authentication is required and scoping of any tokens. Examples;
get-the-authenticated-user
get-a-user