What is Art ?

Art is the human production or creation intended to be attractive, to arouse a positive esthetic assessment.
But there is a problem: the feeling of beauty is subjective. Except certain universally recognized art form, like painting of Matisse

Matisse: Blue nude

 or Renoir,

 Auguste RENOIR: Au coeur de l'intime

 most of art is proned to arguing.

 It is really art ?! Or just a joke...

It is the case of Urban art like grafitti.
I think we can consider a work as a piece if it is innovative and it sparkks off an emotion.

<= Emotion

No Emotion =>

But there is many kind of art: cinema, cooking, photographie, comics... And all those activity have the same common point: they unceasingly evolve. It is the fruit of human hands in opposition with nature. But it draw also inspiration from nature.

To conclude I think there  is two main signs to considere a work as a piece: it has to be innovative an to create a feeling for the person who look at it. But this feeling is not necessarly a feeling of beauty, it can be fear, or sadness. I am sur new kind of art will rise in the years to come, like for exemple digital art.