Trump was given a brown scapular. What’s that?

What exactly is a brown scapular, why are there other colors, and how does enrollment work, anyway?

A video shared widely on social media in recent days shows Donald Trump receiving a brown scapular.

A brown scapular. Sarah sofía at English Wikipedia (CC BY-SA 3.0).

The 33-second video records an encounter between the Republican presidential nominee and a bespectacled figure in a brown habit in a nondescript corridor.  

Filmed at close quarters, with the…