Quick meaning
The number of unique people who saw a piece of content.
Think of it like this
Like counting how many different households received a flyer rather than total flyers sent.
Where you may see this
You may see this on Facebook, Instagram, TikTok, WhatsApp groups, and other social apps.
Why it matters
Understanding the term helps you use social platforms more comfortably and spot risky or misleading behaviour.
Say it simply
Reach means: The number of unique people who saw a piece of content.