Ad blocker refers to a set of technologies that block various types of ad on a website.
Basically, most of ad blockers can be installed as a plug-in for popular browsers.
Rarely, ad blocking is done using a proxy server.

By default, ad blockers block various ad formats: native, images, video etc. Ad blockers can be easily installed and the popularity of this software is forecast to grow rapidly within next years. Most often, users install ad blockers to remove annoying ads of a poor quality.

Special scripts should be coded to have a possibility to identify a user with a certain type of ad blockers. That requires time and specific knowledge. There are no standard free solutions to identify such users.

The percentage of users with ad blockers varies vastly and depends on geography, type of device, website.
On average, 11% of Internet users employ ad blockers worldwide. And this percentage is expected to grow up to 30% within next few years.

Browser plug-ins are the most applicable ad blocking method. While a web page is being loaded, a browser is sending requests to the server in order to get the web page content and ads.
Ad blocking add-ons handle the requests which are sent by the server. All browser requests are monitored and those containing the content from the blacklist are blocked.
“Easylist” is the most known such blacklist. A large community of professionals and Internet users support that list and keep it up-to-date.
Ultimately, users with ad blockers see a web page with empty spaces instead of ads.
For publishers that means losses in their revenue as they are not able to monetize those visitors.

Unfortunately, not. Those users cannot be monetized as they don’t see any ads on a website.
Moreover, advertisers lose a significant part of their target audience.

There are lots of various ad blockers in the Internet. But such tools as Adblock, Adblock plus, AdGuard are used more frequently than others.