PLAIN-LANGUAGE DEFINITION
Reach
Reach estimates the number of distinct people or accounts exposed within a reporting scope.
IN PRACTICE
An example
A campaign with 1000 impressions and average frequency 2 implies estimated reach of 500.
What this does not tell you
Platform definitions and deduplication affect reported reach.
Use the term precisely
When you use this term in a brief or report, include the relevant source, scope and assumptions. An example explains the concept; it is not a benchmark or a promise of results.