What is it?
The free open source cross-platform wide-spectrum blocker / ad blocker browser extension UBlock Origin (uBlock Origin) by Raymond Hill (Gorhill).
Here is how Wikipedia describes this browser extension:
uBlock Origin (pronounced you-block ) is a free and open source, cross-platform browser extension for content-filtering, including ad-blocking.
The extension is available for several browsers: Safari, Chrome, Chromium, Edge, Firefox, and Opera.
uBlock Origin has received praise from technology websites, and is reported to be much less memory-intensive than other extensions with similar functionality.
uBlock Origin’s stated purpose is to give users the means to enforce their own (content-filtering) choices.
As of 2017, uBlock Origin continues to be actively developed and maintained by founder and lead developer Raymond Hill.
Here are the links where you can get uBlock Origin for several different web browsers:
uBlock Origin for Google Chrome & Brave Browser & Chromium
uBlock Origin for Mozilla Firefox
uBlock Origin for Microsoft Edge
uBlock Origin for Opera