It is not money, even though most creative artists will never make a living at what they do best, and could often do with a bit more scratch.
It is not an appreciation of technical abilities, even though that may rightfully underscore years of hard work and a great deal of talent.
The nicest compliment you can give a creative artist, whether a dancer, writer, musician, painter, actor, director, choreographer, photographer, sculptor, or designer is that he or she through their art made you feel something that resonated within you. It doesn't matter what that emotion was -- joy, anger, sadness, longing, fear, peacefulness, anything -- but that it felt real, from your core. This is the highest calling of any art, and the most noble: to connect with other human beings in ways that often transcend words or time. Art helps us to better understand our world and ourselves, the endless quest for knowledge, for knowing.
If you are an artist and have ever received such a compliment, treasure it always. Its value and lasting effect means far more than any award or check you could ever receive.