What is Domain-Driven Design (DDD) in PHP?

Domain-Driven Design (DDD) is an approach to software development focused on modeling the core business domain in code. Key concepts: Entities (objects with identity that persists over time — e.g., User with ID), Value Objects (immutable objects defined by their value, not identity — e.g., Money(100, "USD")), Aggregates (cluster of objects treated as one unit with a root entity), Domain Events (something significant that happened in the domain), Repositories (abstract persistence per aggregate), Services (operations that do not belong to entities), and Bounded Contexts (explicit boundaries where a model applies). PHP frameworks like Symfony are commonly used for DDD because of their flexibility, while Laravel can also accommodate DDD with proper structuring.