An ad blocker is a program that will remove different kinds of advertising from a Web user’s experience online. These programs target certain kinds of ads, such as pop-ups, banner ads and other common forms of online advertisement, allowing a user to surf the Web without annoying distractions or interruptions.
Techopedia explains Ad Blocker
Ad blockers work in many different ways. Some are standalone programs, while others are features of more comprehensive customizing services, or add-ons for a particular browser or operating system. Some browser-specific programs, like PithHelmet for Safari, or other programs for browsers, like Opera, are designed to work well in a particular environment. Others work with Windows or another operating system to block pop-ups or other kinds of ads.
Users have a wide range of options for blocking out different kinds of ads. Some programs delete cookies and other Web markers to effectively limit ads. Web proxy programs like Privoxy can be effective ad blockers. Some users will choose to block Adobe Flash in order to block annoying video ads, which are now common on some websites. There are also freeware programs that may use simple principles to block out advertising.