In Domain-Driven Design (DDD), a model is a structured and simplified abstraction of a domain that maps and documents everything of interest within that domain. It represents the organized and structured knowledge of the problem space, capturing the vocabulary, key concepts, and the relationships among all of the entities within the scope of the domain[3][8]. The model is essential for creating a shared understanding among all stakeholders involved in the project, from software developers to business executives. It serves as a blueprint for the software's design, ensuring that the resulting system accurately reflects the business domain it is intended to serve.
The domain model should be accessible and understandable by everyone involved with the project and should define the vocabulary around the project, acting as a communication tool for everyone involved[3][8]. This is crucial for maintaining a ubiquitous language, a key concept in DDD, which is a common language shared by developers, domain experts, and users to ensure that the software accurately reflects the business domain[2][12].
The model in DDD is not just a diagram or documentation but is implemented in the software code itself, where the structure and language of the code (class names, class methods, class variables) should match the business domain[12]. This alignment between the model and the implementation is fundamental to DDD, as it ensures that the software system is deeply connected to the domain logic, facilitating easier communication, improved flexibility, and a user-oriented design that is aligned with business goals[14][18].
