What noun is often used after customer as part of a compound noun?

The most common noun used after "customer" in a compound noun is "service".

Here are some examples:

* Customer service: The department or individuals responsible for assisting customers.

* Customer service representative: An individual who provides customer service.

* Customer service experience: The overall interaction a customer has with a company.

Other nouns can be used with "customer" to form compound nouns, but "service" is the most common and versatile.