In Domain-Driven Design (DDD), an infrastructure service is a service that provides technical capabilities to an application or system, such as data storage, messaging, authentication, or caching. These services are typically not part of the domain model, but rather provide supporting functionality for the application. They are usually invoked by the application layer or the domain layer, and may be used by multiple parts of the application.

Examples

Some examples of infrastructure services in the context of DDD:

1. Database Service: An infrastructure service that is responsible for persisting the state of domain objects to a database.
2. Email Service: An infrastructure service that is responsible for sending emails to users.
3. Caching Service: An infrastructure service that is responsible for caching data from the domain model to improve performance.
4. Message Bus Service: An infrastructure service that is responsible for managing the communication between different parts of the system.
5. Authentication Service: An infrastructure service that is responsible for authenticating users and managing user sessions.
6. File Storage Service: An infrastructure service that is responsible for storing and retrieving files.
7. Search Service: An infrastructure service that is responsible for indexing and searching data in the system.

These are just a few examples, but there can be many more depending on the specific needs of the domain and the system being developed.

These are just a few examples of infrastructure services, as the exact services needed can vary depending on the specific application and its requirements.