Broadly speaking, a Digital Service is any service that is delivered electronically over the Internet and that customers can access in a self-service mode through a web or mobile interface.
Some of the most common means through which a digital service can be delivered are: a Website, a Mobile App, Cloud computing, such as software as a service (SaaS) or platform as a service (PaaS)... https://learn.servitly.com/docs/what-is-a-digital-service