What one, single word do you believe sums up customer service?

HEARTFUL SMILE ..... it means a lot in customer service

"Commitment" is the word I would like to say.

Commitment to serve and do the right.

Client satisfaction is probably more than one word but it epitomizes what customer service should be about. When your organization develops its business around this principle, you and your colleagues are on the right path.

Meeting/satisfying his requirement

GOOD CUSTOMER SERVICE: GOOD COMMUNICATION+FRIENDLY MANNER= "SATISFACTION" .

I believe the most important thing in customer service is politeness and a yes smile on your face. 

EXCELLENT CUSTOMER RELATIONSHIP

One word that sums up customer service is "Satisfaction".