Glossary
What is reach? Reach and impressions explained simply
How many different people saw your post at least once.
Reach counts people. If four hundred different humans saw your post, your reach is four hundred, no matter how many times each of them scrolled past it.
Reach against impressions
Impressions count showings instead of people, so the same person seeing your post three times adds three impressions and one unit of reach. When impressions run far ahead of reach, the platform kept putting you in front of the same crowd.
Why reach is the one to watch for growth
New people are what grow an audience, and reach is the closest thing you get to counting them. If your reach sits still while you post more, you are talking to the same room louder.
What actually moves it
Posts that hold attention get shown to more people, so the first line and the first three seconds do most of the work here. There is a full read in why your LinkedIn posts get no views.