What is Instagram Reels?

Instagram Reels is Instagram's short-form vertical video format, distributed largely through algorithmic recommendation rather than to existing followers. That distribution model is the reason it matters commercially: a Reel reaches people who do not follow the account, which makes it the platform's main discovery surface, while feed posts and Stories skew toward an audience already acquired.

Practical specifications are stable — 9:16 vertical, up to 90 seconds for most accounts, with captions expected rather than optional given how much viewing happens with sound off. Performance concentrates in the opening seconds, and the metrics that predict distribution are watch-through and shares rather than likes. Two constraints catch brands out. Visibly watermarked content reposted from TikTok is downranked, so cross-posting requires exporting a clean file rather than saving from the other app. And the format rewards volume and iteration more than production value: accounts that publish consistently and read the retention curve outperform accounts that publish occasional polished pieces.