A pop-up window is a window that gets automatically displayed on your browser screen when you open specific web sites. These windows will normally be of the size less than that of your browser window and will be displayed usually in the background.
By default, Pop-up windows are blocked in Google Chrome. The following How-to guide will walk you through the steps on how to enable and disable Pop-up windows in Google Chrome web browser.
1) Click on the Wrench (Tools) icon that you find at the extreme right corner of the URL bar and then click on Options from the drop down menu.
2) You will now be redirected to the Options window in a new tab on your browser.
3) In the Options window, select the Under the Hood panel.
4) Then, in the right pane of the Under the Hood settings window, click on the Content Settings button.
5) Now, in the Content Settings pane thus revealed, navigate to the Pop-ups option and there you can see that the pop-ups feature is disabled by default.
6) To enable the pop-up windows feature, just select the radio button that says Allow all sites to show pop-ups.
7) Close the Options tab on your browser to exit from the Options window.
You may also want to know How to enable and disable pop-ups feature in Firefox.