Social engagement
Social engagement counts the meaningful interactions a piece of content receives: likes, comments, saves, shares, and (on some platforms) clicks. The headline measure of content resonance.
Engagement is not all created equal. Likes are the lowest-weight signal (cheap to give); comments and shares are higher-weight (require effort); saves are often the highest-weight (signal "I want to return to this"). Platform algorithms weight these signals differently when deciding whether to push a post to more people — comments and shares typically count more than likes on Instagram and LinkedIn.
Engagement rate, the standard normalisation, is engagement divided by reach (or impressions, depending on platform). It controls for distribution differences across posts and accounts: a small account with high engagement rate is producing content more resonant than a large account with low engagement rate, even if the absolute engagement numbers favor the larger account.
Engagement is the lagging indicator of content quality. Voice, format, and timing are the leading indicators that produce it.