Rating (schema.org)
Rating is a schema.org type that describes a single rating or score, for example on a scale of one to five stars, and is usually used inside Review or AggregateRating.
In practice
Rating rarely stands on its own; it is part of larger structures such as Review, where it represents the actual score given by an individual user. Stating bestRating and worstRating matters, so that it is clear which scale was used – one to five rather than one to ten, for instance.