What are Slack Posts and how to use them

I have been using Slack for a great number of years. But today I discovered a simple feature, that I would have loved to know more about quite some time ago: Slack Posts.

A Slack Post can be created on any desktop device, using a simple /post command. It creates a document, that lives in Slack, can be shared within a channel and edited by all of those who have access to it.