Impressions
Impressions count the total number of times content was displayed on screens, including repeat views by the same account. One person who sees a reel three times adds three impressions but only one to reach. The gap between the two numbers shows how often people are coming back.
Why it matters for creators
Impressions read against reach tell you about repetition. If 10,000 impressions came from 4,000 accounts, people are seeing the post more than once — returning to it, rewatching it, or meeting it again in a new feed. For reels, a wide gap often means the hook holds up to a second viewing.
Two practical notes. Instagram's own insights have been consolidating this idea under "views" in recent years, so the label can differ from the concept. And impressions alone can't tell a returning fan from someone who scrolled past twice — read them next to reach and engagement, not instead of them.