A persistent interface that exposes a needed functionality. It is one or more processes that do not have a stop time.
In high performance computing, a service is typically a task manager, application programming interface, or database. HPC systems sometimes have protected or isolated environments explicitly for services. Services typically run alongside applications that interact via client APIs or web interfaces. In Kubernetes, a service describes exposing a network interface of a pod. This is a prime example of the same term meaning fundamentally different things.
Converged Computing Authors. "Services." Converged Computing Community Space 04 May 2024, https://converged-computing.org/docs/services/ (accessed 04 May 24). [doi]