Pop-up ads are a form of advertising on the internet designed to attract traffic to websites or capture email addresses. Pop-up ads generally open in a new window on your browser displaying an advertisement. Another variation of the pop-up ad is the pop-under ad, which does just what it sounds like it would do. A pop-under window creates under the active window and is generally not seen by the user until they close the window they are currently in.
Some pop-ups are harmless and actually help when navigating through some websites or when installing some programs on your computer. However, many pop-ups contain viruses, malware, spyware, or pornographic images which can cause your computer to install unwanted programs or attempt to steal information from your computer.
There tends to be more of an issue with pop-ups in the more indecent websites that one might visit. Not all websites that have excessive pop-up windows are indecent though. Many reputable websites use pop-up ads for marketing purposes.
Although most pop-ups are harmless, they can become quite an annoyance when you are using the internet and it is difficult to know when a harmful window might pop up. To avoid dealing with pop-up windows while surfing the internet, it is wise to install and use pop-ups blockers either provided through your web browser, internet provider, or downloaded through a third party.
In some cases you may want to be able to have the pop-up feature for some websites. This can be accomplished by temporarily disabling your pop-up blocker, although this method is not advised as it can allow unwanted content to slip through. Another option on most internet browsers is to hold down the ctrl key while clicking on the link you wish to open. This will allow you to bypass the pop-up filter for that particular page while keeping it running for all other pop-ups that might be trying to get through.