When a ServiceNow instance requests information from a web service, ServiceNow is the web service:

When a ServiceNow instance requests information from a web service, ServiceNow is the web service consumer. A web service consumer is an application that sends requests to a web service provider and receives responses from it. A web service provider is an application that exposes its functionality as web services. A web service publisher is a person or organization that publishes web services for others to use. A web service specialist is a person who has expertise in developing or using web services. Reference: Web services