Paid reach
The number of unique people who saw your content because you paid to promote it — boosted posts and ads.
Paid reach is the audience you reach by spending money — boosted posts, sponsored placements, and ad campaigns — as opposed to organic reach, which the platform hands you for free. It's the half of reach you can buy on demand.
Paid reach is predictable and fast, which makes it useful for launches and audience-building, but it stops the moment the budget does. Its cost is usually quoted as CPM — the price per thousand impressions — and a cheap CPM that reaches the wrong people is no bargain.
See also