Domain Driven Design
In plain terms
Designing software around the real business domain and its language.
Going deeper
DDD aligns code structure with the business concepts and terminology, using bounded contexts and a shared 'ubiquitous language' so software models reality faithfully. It shines in complex domains.
Under the hood
Strategic patterns (bounded contexts, context maps) align teams; tactical patterns (aggregates, entities, value objects) structure code around the domain model.
Examples
E-commerce 'Order' aggregate, ubiquitous language with domain experts, microservice boundaries.
Think of it like...
Like architects designing a hospital by deeply learning how doctors and nurses actually work, rather than imposing a generic floor plan.