How to add addons in Blender

In this video you can see how to add addons aka plugins in Blender.

Some addons that I've found useful in blender is fspy (for correcting the perspective), Hard ops, Box cutter, Cablerator and shortcut VUr (if you want to make tutorials you can use this addon. It shows 3 mouse buttons and the keystroke that has been pressed on your monitor).