The best way to explain what art is, is by looking at the art work of Piet Mondriaan.
Why is it Art? Those are just some lines and some colored squares ... why is it art?
Piet Mondriaan was born in 1872 in the Netherlands. He went to the art academy, which at that time was a well respected craft and he learned how to make 'paintings'. At that time, 'paintings' were basically 'photographs' ... they were as realistic as possible, little snapshots of the natural world, especially landscapes were particularly popular.
For his graduation, he needed to come up with such a painting, so he sat outside his parents house and painted the sea, with that one tree. After his studies, he traveled around Europe and he learned the new styles, like expressionism and impressionism. So, he kept painting the same tree, but integrated the new style elements he learned in each new painting. And that's how that one same tree kept evolving.
The Red Tree
The Gray Tree
Blooming Apple Tree
"Aha, Mondriaan's artistic interpretation of a tree."
Well, he didn't went from very realistic landscape paintings to black lines and colored squares in 1 day, it took him 40 years. This while if we were to look at the the history of the country he was living in, during the same period; the Netherlands evolved from a agricultural nation into an industrialized nation ... the parallels are remarkable.
"Art Reflects the Spirit of the Times"