One-bit message

A one-bit message is a type of communication that has no personalized or specified content, and as such transmits only a single binary bit of information. It signals an intent and a thought, but does not specify what it is. Marc Andreessen describes "one-bit communication" as having no content other than that it exists. Examples of one-bit messages in the real world include the sound of car horns, police sirens, and “open” signs. Telephone calls which are deliberately terminated before being answered are also an example of one-bit communication.
In probability.
One-bit messages can be used to communicate the outcome of situations with two potential outcomes, such as a coin toss.
Online messaging.
In the online world one bit messages solve a set of communication initiative problems:
There are several platforms that enable sending one bit messages including Yo and the Facebook poke.