Bounded Context

Bounded Context is a central pattern in Domain-Driven Design. DDD deals with large models by dividing them into different Bounded Contexts and being explicit about their interrelationships.

DDD is about designing software based on models of the underlying domain. As you try to model a larger domain, it gets progressively harder to build a single unified model. Different groups of people will use subtly different vocabularies in different parts of a large organization. The precision of modeling rapidly runs into this, often leading to a lot of confusion.

In the past we were advised to build a unified model of the entire business, but DDD recognizes that we've learned that "total unification of the domain model for a large system will not be feasible or cost-effective". So instead DDD divides up a large system into Bounded Contexts, each of which can have a unified model - essentially a way of structuring multiple canonical models.

Bounded Contexts have both unrelated concepts (such as a support ticket only existing in a customer support context) but also share concepts (such as products and customers). Different contexts may have completely different models of common concepts. DDD's strategic design goes on to describe a variety of ways that you have relationships between Bounded Contexts. It's usually worthwhile to depict these using a context map.

original author: Martin Fowler
source: https://martinfowler.com/bliki/BoundedContext.html