CES (Customer Effort Score) is a KPI that measures customer's experience with a product or a service. The CES score is about how much effort was required to use the specific product or service. CES survey question could be, for instance:
The company made it easy for me to solve my issue.
It is also possible to ask a customer:
To what extend do you agree or disagree with the following statement.
"The company made it easy for me to handle my issue."
After both questions, a customer answers on a scale "very difficult" or "very easy" or something between.
CES reveals the pain points in the customer interactions. The tool can be used after a customer's issue is solved, for instance, after a call, a chat or a service. By asking customer satisfaction surveys, it is also easy for the company to start developing its processes and improve customer loyalty based on the customer feedback data.
The main idea in CES is to get insights of the processes and experiences the customers go through so they can be improved to be as effortless as possible. CES is not the tool to provide information about business overall or the customer desires or challenges. For those cases, there can be utilized other customer experience KPI's, such as NPS or CSAT. You can read more about NPS here, and CSAT here.