Extra browser window of commercials that open automatically on browsing web…

Concept

Browsing the web exposes a user to several distinct categories of unwanted content, and each has a precise name. A pop-up is a secondary browser window or frame that a web page opens automatically, without the user clicking to request it; when its content is advertising, it is a pop-up advertisement. The defining trait is the automatic opening of an extra window carrying commercial content.

Applying it here

The stem describes an extra browser window of commercials that opens automatically while browsing. That description maps exactly onto the automatic-extra-window behaviour of a pop-up, so the term being defined is Pop-up.

Why the other terms do not fit

• Spam refers to unsolicited bulk messages, typically email, not a browser window that opens during web browsing.

• Virus is a self-replicating malicious program that infects files or systems; it names a type of malware, not an advertising window.

• Phishing is a deception technique that tricks a user into revealing credentials or data via fake pages or messages; it describes an attack method, not an auto-opening commercial window.

Only the automatic extra advertising window matches the definition, so the answer is Pop-up.