diff --git a/README.md b/README.md
index 9e6ac2b..eb2b4fd 100644
--- a/README.md
+++ b/README.md
@@ -37,9 +37,13 @@ Drag a window to the edge of the screen. When the mouse cursor reaches the edge
 
 ### Ignore an app
 
+Ignoring an app means that when the app is frontmost, keyboard shortcuts are un-registered from macOS. When the app is no longer frontmost, keyboard shortcuts are re-registered with macOS. This is useful for apps that have the same shortcuts like Rectangle and you do not want to change them.
+
 1. Focus the app that you want to ignore (make a window from that app frontmost).
 1. Open the Rectangle menu and select "Ignore app"
 
+To un-ignore an app that you have selected to ignore, simply bring that app frontmost again, open the Rectangle menu, and deselect "Ignore".
+
 ## Execute an action by URL
 
 Open the URL `rectangle://execute-action?name=[name]`. Do not activate Rectangle if possible.