- Edited
Vlad Given that one doesn't always know in advance whether an unfamiliar website (or a different page on, say, eBay) is going to have one of Facebook's "like" buttons, I would think one would wind up having to create a new profile whenever opening a search result on an unfamiliar website (or whenever clicking on a search result in eBay). The Facebook container takes care of that for you. In Firefox, if you open a page that has a Facebook "like" button on it, the extension's icon shows a purple dot with an exclamation point, and if you click the icon you get a message letting you know that Facebook doesn't see that you've been to that page, but warning you that if you click the "like" button, that page will be tied to your Facebook identity (I'm assuming that you'd have to be signed in to Facebook in order for this to happen, but I don't know for sure).