very useful for multitasking
tip for new users: you can change the shortcut in extensions settings "Manage Extension Shortcuts"
I have it set to alt+w since that is what I was used to

the developper should add in the description that we can also switch to the previous active tab by clicking on the icon add-on (it is the main use i have of this add-on).

and i'd like to answser to an other comment about the shortcut modification:
you can change it easily with firefox here is how to do https://support.mozilla.org/en-US/kb/manage-extension-shortcuts-firefox link found thanks to this page https://addons.mozilla.org/fr/firefox/addon/active-tab-history/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search

Very good! I was used for years "Tab Mix Plus" for reach the last tab focused. Now, the new web extension (Tab Mix Links), no more do this. I try, from time to time, to look for the best extension to do this, hoping that it will soon be possible, with a click on the page title, to return to the previous Tab.

Tut genau das, was es soll. Habe schon länger nach so einem Add-on gesucht.

At last an extension that can go to previously opened tab!
Ctrl + Tab doesn't work on My Linux FireFox 52 (it just go to next tab), so this plugin made my day.
Thanks!

perfect
عالی بود