Twitter is an information network that brings people closer to what’s important to them.
Every day, millions of people turn to Twitter to connect to their interests, to share information, and find out what’s happening in the world right now. Anyone can read, write and share messages of up to 140 characters on Twitter. These messages, or Tweets, are available to anyone interested in reading them, whether logged in or not. Your followers receive every one of your messages in their timeline – a feed of all the accounts they have subscribed to or followed on Twitter. This unique combination of open, public, and unfiltered Tweets delivered in a simple, standardized 140-character unit, allows Twitter users to share and discover what’s happening on any device in real time
for more info: https://business.twitter.com/basics/what-is-twitter/