Pop-ups refer to windows that are displayed on your computer screen for the purposes of advertising. Pop-ups occur when you browse certain websites. Some websites are funded by selling advertising space, some of which decide to hawk their wares by flooding your computer screen with clever ads.
How Pop-Ups Work
Pop-ups work using the same mechanism built in to web browsers, such as Internet Explorer, to open a URL in a new window. Sometimes this can be a useful function; for example, http://www.weather.com may use a pop-up window to display an urgent weather bulletin. But, in general, they are an annoying waste of your time.
How to Get Rid of Pop-Ups
Just like spam and other scams, pop-ups get a response rate or else companies would not use them any longer. So, first and foremost, stop clicking on them. Your PC will not run faster, you will not win free money by clicking on the monkey, and a pop-up IQ test is pretty ironic actually.
Second, get a pop-up blocker. Microsoft Internet Explorer 6 Service Pack 1 (SP1) running under Windows XP SP2 now has a built-in pop-up blocker. Turn it on by clicking Tools > Pop-Up Blocker in Internet Explorer.
If you are not running this version of Windows or Internet Explorer, download any number of free pop-up blockers and use it.