What are Adblockers?

Adblockers are software utilities that are included in modern internet browsers such as Firefox, Safari and now even Google Chrome that prevent certain or even all ads from being displayed in the browser.  They initially prevented annoying pop-up adds and flashing banner adds but they can even block text ads displayed along search results. Apple, for instance, has included a baked-in Adblocker in its mobile phone activated by default.