Domain Driven Design (DDD) is a software design approach that focuses on understanding and reflecting the business in code.
The main concepts of DDD are: domain, entities and value objects, aggregates and aggregate roots, domain services, domain events, and bounded contexts.
The domain represents the business problem being solved and is developed using a ubiquitous language to align developers and domain experts.
Aggregates are groups of related domain objects treated as a single unit, with the aggregate root controlling access to other objects within the aggregate.