Internal customers are people INTERNAL TO YOUR organization or business that receive and/or depend on your work product or services. They differ from regular customers in the sense that they don't pay for receiving your work product, but they share the characteristic of using your work product. Internal customers may include your colleagues (but not necessarily all your colleagues), and other departments who you might not even have direct contact with.
Importance of Considering Internal Customers As Customers
We normally associate the importance of customers in terms of their "paying" salary and keeping the company in business. With internal customers, the issue is different. It has to do with internal effectiveness and efficiency. That's because very little that happens in organizations occurs in isolation. An effective organization requires that each part of the organization recieves from other parts, what it needs to do its job well. If the internal customer doesn't receive what it needs, then the organization slows down, and can't do what it needs to do in an efficient manner.
Human Resources - An Example of Internal Customer Service
Let's consider the HR (human resources) department. While it has external customers - for example, people who apply for jobs from outside, it also has many internal customers. It provides information to employees on pay, is often the repository for performance management documentation, and serves the managers, executives and employees within the organization. Ideally, the HR department should be focusing on serving the needs of its customers who rely on the reports, information, and other services it provides, in order to carry out their functions.
In a hiring situation, HR functions as trusted advisor, helps guide managers in the hiring process, ensures laws are followed, and so on. So, in fact, HR's primary customer is to serve internal customers. If it does not do so, it starts to become a roadblock to efficient operation.
Information technology is another department who's primary purpose is to enable others inthe organization to do their jobs.