Returning viewers
Also called returning viewer rate · new versus returning viewers
The share of a video's views that came from people who have watched the channel before, reported in YouTube Studio's Audience tab alongside new viewers.
In more detail
YouTube splits every video's audience into new and returning viewers and reports the split as a proportion of views rather than an absolute count. A channel still finding its audience typically skews heavily toward new viewers on most uploads; a channel with a built-in habit-forming audience, the kind sleep or ambient content depends on, shows a rising share of returning viewers over time.
Example
Two videos with identical view counts can carry very different signals: one drawing almost entirely new viewers is reaching people for the first time, while one carrying a high returning share is being sought out by an audience that already knows the channel, which behaves differently for subscriber growth even at the same view count.
Why it matters
A rising returning-viewer share is one of the clearest signs that a channel has moved past being discovered per video and started building a habit, which is the point at which growth compounds instead of resetting with every upload.