What is a Core Domain?

In Domain-Driven Design (DDD), a Core Domain refers to the most critical part of the business domain that is essential for the success of a project or organization. It encompasses the areas of the business that give the organization a competitive advantage and are strategically important for achieving its goals.

Here’s a breakdown of key aspects of the Core Domain in DDD:

1. Strategic Importance: The Core Domain represents the heart of the business, where the most value is generated. It is the part of the system that differentiates the company in the market and must be treated with extra care.

2. Focused Development Efforts: Since it is the most important area, the team should allocate its best resources (in terms of expertise, time, and energy) to building and refining this part of the system.

3. Clear Boundaries: In DDD, the business domain is often divided into multiple subdomains (e.g., Core Domain, Supporting Domains, and Generic Domains). The Core Domain should be well-defined and separated from other less critical subdomains.

4. Customization and Complexity: Unlike Generic or Supporting Domains, which can sometimes be off-the-shelf or simplified solutions, the Core Domain often requires custom solutions because it deals with the unique complexities of the business.

5. Domain Experts Involvement: In the Core Domain, close collaboration with domain experts is crucial. Their deep understanding of the business helps create a precise model that addresses the most critical aspects of the domain.

Example:

Imagine a company that offers an online marketplace. While the system might have various functionalities like user management or payment processing, the Core Domain could be the recommendation engine that drives personalized shopping experiences. This engine might give the company a competitive edge, so it’s treated as the most critical part of the system.

In summary, the Core Domain is the key part of a business domain that demands strategic focus, as it is the source of the organization’s main value and competitive advantage.