Half and half (or half cream in the UK) is just what the name implies. it is half milk and half heavy cream. its fat content is about 10%. Its primary use is as a substitute for a full heavy cream in a recipe ingredient. it provides nearly the same texture, richness and creaminess without the intense fat content.
Because of its higher water content it cannot be used as a whipping cream. However, any cream sauce such as Alfredo or mock cheese sauce is a great home for half and half.
In desserts such as panna cotta, it will deliver a smoother, more consistent result..