Domain-Driven Design (DDD) is a software development methodology that emphasizes the importance of modeling a software system based on the real-world domain it represents. DDD is particularly useful for complex applications with intricate business logic. It was introduced by Eric Evans in his book “Domain-Driven Design: Tackling Complexity in the Heart of Software.”

Basic Concepts in DDD

Domain: The central focus of DDD is the domain, which represents the core business problem that the software addresses.
Entities: These are objects with distinct identities and lifecycles within the domain. They have attributes and behaviors.
Value objects: Value objects are objects without distinct identities. They represent attributes that are conceptually distinct within the domain.
Aggregates: Aggregates are groups of related entities and value objects treated as a single unit. They are often responsible for enforcing consistency and maintaining data integrity. In other words, you are creating meaningful relations between two or more value objects.
Repositories: Repositories provide an abstraction for data access, allowing the application to interact with aggregates.
Services: Services represent actions or behaviors that don’t naturally belong to a single entity or value object.
Bounded contexts: A bounded context defines a specific, self-contained part of the domain where the domain model and its concepts have clear and consistent meanings.

DDD helps developers create software that is closely aligned with the business domain, making it easier to understand, maintain, and evolve over time.