The Internet is a dangerous place. Some companies are spying on you and, want to get as much of your private information as possible. What are your interests? What sites are you visiting? What can we sell you? Your information is the new gold.
As a countermeasure, a range of browser plugins has been developed to enhance your privacy by blocking information-gathering attempts. A few of the most common and well-known extensions are uBlock Origin and Privacy Badger. These plugins all use Manifest V2, which grants them certain functionality and determines their permissions in the browser.