What is People Reached?
It is not Profile Views, as you might imagine Profile views is the number of people that have visited your profile page.
People Reached is the approximate number of people that your posts have been seen by. (Although that's a very loose interpretation. There is more info on that here: "We're working on a new stat to help convey the reach of your posts here").
Source Difference between Profile Views and People reached - Meta Stack Exchange
How is it calculated?
Ultimately we reduced our criteria to:
Views of pages where your helpful posts had some decent probability of being seen.
That doesn't mean we know the visitor scrolled to your post, or that
your answer helped them - we simply don't track that. But we should be
able to estimate the likelihood of a given question or answer been
seen as useful by viewers without enabling the 25th answer on an
insanely popular post to get a lucky up-vote and credit all the views
to the new author.
That's how we got to the current method, which counts views on the
- Non-deleted only
- Answers - Views of the parent question for answers that are:
- Non-deleted AND
- Score > 0 AND
- Also meets one or more of the following criteria:
- In the top 3 answers OR
- Is the Accepted Answer OR
- Score at least 5 OR
- Has at least 20% of the total vote count
(Note on closed questions: we originally were excluding closed
questions, too, but it seemed to cause more harm than good: the ones
that never should have been here almost all get closed before
attracting many views, so including them very rarely matters. But the
ones that are closed with a ton of views almost all were permissible
back in the day, so having the score plummet when the rules evolve
seemed more harm than the alternative, since the impact is so small
Source We're working on a new stat to help convey the reach of your posts here - Meta Stack Exchange
Why should I care?
It tells you how helpful your contributions are to other users. Whether you care about that is up to you.