Web browser:

All major web browsers allow the user to open multiple information resources at the same time, either in different browser windows or in different tabs of the same window. Major browsers also include pop-up blockers to prevent unwanted windows from "popping up" without the user's consent.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What can be open without the user's consent in a window?
unanswerable