What is Reach?
The algorithm for Reach is based on a source’s audience size. You can estimate how popular a given source is and how powerful their mention of you can be. Quite helpful, isn’t it?
Reach comes in handy when you're selecting influencers to work with on your marketing campaigns - you can choose the right people and evaluate how well your campaigns are doing.
You can see the reach of a given author under Sources in your project.