In [[Software architecture]], particularly in [[Domain-Driven Design (DDD)]] and [[Ports and Adapters|Hexagonal architecture]], Application Services act as orchestrators, coordinating interactions between the [[Domain Model]] and external dependencies. They isolate domain logic, keeping it focused on business rules while managing external communication and transactional logic in the application layer. This boundary ensures the domain remains agnostic of infrastructure concerns, aligning with the [[Single Responsibility Principle (SRP)]]. An application service can be a client to a [[Domain Service]].