A "friendly third-party" cookie is a type of cookie that is set by a domain that is different from the one that the user is currently visiting, but is still considered to be trustworthy and part of the user's intended browsing experience.
Unlike "third-party" cookies, which are often set by advertisers and other third-party providers to track users across different websites, friendly third-party cookies are set by domains that are related to the content or functionality of the site that the user is visiting.
For example, if you visit a news website that embeds a Twitter feed on their homepage, the cookies set by Twitter in this case would be considered "friendly third-party" cookies, as they are used to provide a useful feature (the Twitter feed) that is part of the intended user experience of the website.
In contrast, if the website embedded an ad from an advertiser, the cookies set by the advertiser would be considered "third-party" cookies, as they are not directly related to the content or functionality of the website, and are instead used for tracking and advertising purposes.
In summary, a "friendly third-party" cookie is a cookie set by a trusted domain that is different from the one the user is currently visiting, but still serves a relevant and intended purpose within the user's browsing experience.