Pop-up ads or pop-ups are a form of online advertising on the WWW World Wide Web intended to attract web traffic or capture email addresses. It works when certain web sites open a new web browser window to display advertisements. The pop-up window containing an advertisement is usually generated by JavaScript, but can be generated by other means as well.

Harmful examples of some pop-ups also claim to be the best Anti-Virus software you can get but most of the time can infect your PC with malware like Zlob and Vundo.