One of the most common issues people have when setting up Intercom first is they forget to include their App ID in the above library code and copy and paste it into their site. The problem is you won't see any error message and Intercom will not show up when you boot the Messenger in the next step. You can set it using a var as noted in the above example or manually in the code itself. You might need to include the App ID in multiple places so using a var is generally a good idea.