diff --git a/Quick-guide:-popup-user-interface.md b/Quick-guide:-popup-user-interface.md
index a597b29..073fdcb 100644
--- a/Quick-guide:-popup-user-interface.md
+++ b/Quick-guide:-popup-user-interface.md
@@ -71,3 +71,8 @@ And I had click-to-play enabled in all cases, i.e. it could have been worse (exc
 #### The site-based tools
 
 ![Popup UI](https://raw.githubusercontent.com/gorhill/uBlock/master/doc/img/popup-1g.png)
+
+The first (left-most) icon in the above figure is the popup blocker. By default popups are allowed unless there is a filter to block them. When this setting is turned on, **all** popups will be unconditionally blocked for the current site, regardless of filters.
+
+The second icon is to turn off strict blocking for the current site. By default strict blocking is on.
+