s/protocol/abstraction layer/ What is great about Twitter is that it allows both the sender and the receiver to choose if they want to interact over the web, t

s/protocol/abstraction layer/ What is great about Twitter is that it allows both the sender and the receiver to choose if they want to interact over the web, through an app, via SMS or even email (receiving DMs). Take the lowest common denominator across all platforms (no subejct, max 160 chars in SMS) and sit in the middle as an abstraction.