Facebook engagement rate refers to the measurement of how actively and frequently users interact with a particular Facebook page or post. It is calculated by dividing the total number of engagements (such as likes, comments, shares, and clicks) by the total number of followers or reach. This metric is used to evaluate the level of audience involvement and interest in a brand or content on Facebook, and can help businesses and individuals gauge the success of their social media efforts. A high engagement rate indicates a strong connection with the audience, while a low rate may suggest a need for improvement in content or strategy.