SameSite

Overview
SameSite allows a server define a cookie attribute making it impossible to the browser send this cookie along with cross-site requests. The main goal is mitigate the risk of cross-origin information leakage, and provides some protection against cross-site request forgery attacks.

The "SameSite" attribute is not fully implemented yet. At the time of this article the attribute was defined in a RFC draft available here https://tools.ietf.org/html/draft-west-first-party-cookies-07.