DDD is not an architecture — it's a way of thinking about software design starting from the business domain. An approach that prevents years of technical debt by laying the right foundations.
Domain-Driven Design, conceptualized by Eric Evans in his famous Blue Book of 2003, starts from a simple observation: the most difficult software to maintain is software whose code doesn't resemble the business it models. When developers and business experts don't speak the same language, misunderstandings accumulate layer upon layer until the system becomes impenetrable.
The Ubiquitous Language concept is the first step. It involves creating a shared vocabulary between tech and business teams, directly reflected in the code: class names, method names, variable names. An Order in Java should mean the same thing as an order in the commercial manager's mind. A Bounded Context then delimits zones where this vocabulary is valid — the concept of "Customer" doesn't have the same attributes in the billing context as in the support context.
In practice, DDD applies primarily to complex domains with heavy business logic. For a simple CRUD, it's over-engineering. But for complex pricing systems, multi-step workflows, or changing business rules, investing in DDD modeling upfront saves months of later refactoring.
→ See also: Hexagonal architecture · Microservices vs Monolith