Extensions add useful features to your browser, e.g. the Keeper password manager. But they can also read everything that happens in your browser. So only install verified extensions from official stores.
Recommended by it-tects
Keeper (publisher: Keeper Security): fills in passwords from Keeper automatically.
uBlock Origin Lite (publisher: Raymond Hill): ad and tracker blocker, already installed on managed devices. See “Exclude a website from the ad blocker – uBlock Origin Lite”.
Microsoft Edge
In the top right, open … › Extensions › Get extensions for Microsoft Edge.
Search for the name and check the publisher.
Click Get and then Add extension.
Pin the extension using the puzzle icon next to the address bar.
Google Chrome
Open the Chrome Web Store.
Search for the name and check the publisher.
Click Add to Chrome and then Add extension.
Pin the extension using the puzzle icon.
Mozilla Firefox
Open menu (≡) › Add-ons and themes, search for the name and click Add to Firefox.
Beware of dangerous extensions
Only install from official stores, never via links in emails, pop-ups or ads.
Check the publisher: Fakes often have almost the same name. Look for the right publisher and many users or ratings.
Read the permissions: “Read and change all your data on all websites” is normal for Keeper or ad blockers, but not for a calculator or wallpaper.
Typical traps: free PDF converters, coupon and shopping helpers, free VPNs, “download accelerators” and supposed security extensions.
Clean up: Remove extensions you no longer use (puzzle icon › Manage extensions).
Extensions may be blocked on company devices. Request the extensions you need from support.