what is art

i dont really know how to define art. I think that art is very subjective. It is also very personal. to me I could look at an amazing painting and say, there, that is art! Someone else could look at it and say no, its just some paint on a canvas. Technically he is more correct. But are either of us wrong. I dont have a definition for art. But i do have somewhat of an understanding. I can see things and know, from my opinion if they are art or not. That's what art is about, the interpretation of the viewer. When an artist is creating art they are creating it with the intention of someone to see it and have a certain reaction. For someone to look at their art and find personal meaning within. If it is that they see it and it makes them cry, or even if it as simple as looking at it and thinking that it looks cool.
The question of is grafiti art. In my opinion sometimes yes, and sometimes no. So when you are driving up to LA and you see huge murals of gang names on the sides of the freeway, that is art. It is elaborate and beautiful. So in that sense, that grafiti is definitley art. But when someone just paints a few letters of their gang on a trash can, that is not art.