bearer token is a access token implementation defined in the OAuth 2.0 Authorization Framework
The token may be:
Any party in possession of a bearer token (a bearer) can use it to get access to the associated resources (without demonstrating possession of a cryptographic key) because the token is:
You will find it in the authoritzation header of a HTTP request
Authorization: Bearer <token>
Authorization: Bearer some+base64+string
When an authentication is bearer-only, it means that the authentication requires a authorization header