Why does clicking a website open an ad in a new tab?

Why websites do it

Banner ads on free streaming, download and comic sites pay very little, and many big ad networks won't work with those sites at all. Pop-under networks will, and they pay per tab opened. So the site's goal is simple: turn as many of your clicks as possible into ad tabs. That is why it often happens on the first click, again on the second, and again after you return to the page.

The three tricks you are seeing

1. The hidden script

A script listens for any click on the page. When you click, it opens a tab to an ad address. Often it opens the tab behind your current one, so you only notice later, which is where the name pop-under comes from. Because a real click happened, the browser's pop-up blocker lets it pass.

2. The click-anywhere trap

The site lays an invisible link over the video player or the whole page. You think you are pressing Play, but you are clicking the invisible link, which opens the ad. After the first ad, the layer often removes itself, so your second click finally starts the video. That is why "you have to click Play twice" on some sites.

3. The tab swap (tab-under)

This one is sneakier. When you click, the page opens a copy of itself in a new tab, then quietly sends your current tab to an ad. You end up looking at the ad, and the page you wanted is now in a different tab. It gets past many blockers because the new tab is on the same website.

Why your pop-up blocker misses them

Chrome blocks pop-ups that a page tries to open without any action from you. But it cannot know whether a click was meant for a link or was borrowed by an ad, so it allows tabs that open as a direct result of a click. All three tricks above are built around that rule. More detail in why Chrome's pop-up blocker doesn't stop ad tabs.

Are these ad tabs dangerous?

Most are just annoying, but the pages they open are low quality by nature: fake prize pages, "your phone has a virus" warnings, push-notification prompts and download buttons for things you didn't ask for. A good rule: close them without clicking anything inside, and never allow notifications or install files from a tab you didn't open on purpose.

How to stop them

AdTabBlock is a free Chrome extension built for exactly these three tricks. It stops the hidden script before the tab opens, disables invisible click-anywhere links, keeps your current tab in place during a tab swap, and closes anything that still gets through. Links you click on purpose, Ctrl or Cmd + click, and sign-in or payment windows keep working.

Want to see the tricks in action safely? Our test page recreates all three with a harmless example page, so you can check whether your browser is protected.