Entities & Relationships

Define What Exists

Every domain contains things that matter.

Customers.

Products.

Contracts.

Properties.

Accounts.

Orders.

Cases.

Resources.

Organizations.

These are the entities through which the business understands its own reality.

Entities Give the Domain Structure

A domain specification identifies the entities that exist and the information that defines them.

But entities rarely exist in isolation.

A customer may own accounts.

An order may contain products.

A contract may belong to an organization.

A claim may reference a policy.

Relationships connect these concepts into a coherent domain.

Meaning Through Relationships

The meaning of an entity often depends on its relationships.

A marketplace is defined not only by buyers and sellers, but by the relationships between them.

A legal process is defined not only by documents and cases, but by the relationships connecting parties, authorities, obligations and decisions.

Relationships therefore become part of the domain's formal structure.

From Data Model to Domain Model

This is more than describing database tables.

A domain model represents the meaning and structure of the business.

The objective is not simply to store information.

It is to represent the world the software is responsible for understanding and operating.

Define what exists, how it connects, and the structure that gives the domain meaning.