The idea is take even further in DDD. A core idea is to allow the creation of data-graphs which are always in a valid business state. These so called aggregate

The idea is take even further in DDD. A core idea is to allow the creation of data-graphs which are always in a valid business state. These so called aggregates can only be created from a factory to avoid bad initialization. This way you never need to make ad hoc validations to be “ really really reallysure”.