Ad blocks are browser extensions from google chrome to block web requests that download content into the browser.
In simpler words ad blockers stop ads from downloading on your browser. Making web pages to load faster and offer a better browser experience.
Their job is to filter!
When you visit a website ad block checks to see if it exists on these filter lists, if yes then request for external content is blocked and you won’t see ads downloaded on the webpage.
*The lists are maintained by a third party community not associated with the developers of ad blockers or ad companies.
Is it necessary to have it?
Uh, okay…It is technically harmless to you as a person and It benefits companies to have their products reach the audience they target leading to a possible customer gain.
They do slow down the browser, also very annoying. But not bad though!