Abstract art is art that does not attempt to represent an accurate depiction of a visual reality but instead use shapes, colors, forms and gestural marks to achieve its effect. 

abstract art, also called nonobjective art or nonrepresentational art, painting, sculpture, or graphic art in which the portrayal of things from the visible world plays little or no part. All art consists largely of elements that can be called abstract—elements of form, colour, line, tone, and texture. Prior to the 20th century these abstract elements were employed by artists to describe, illustrate, or reproduce the world of nature and of human civilization—and exposition dominated over expressive function.

Abstraction literally means the distancing of an idea from objective referents. That means, in the visual arts, pulling a depiction away from any literal, representational reference points. You can also call abstract art nonrepresentational art.

Abstraction can be traced to Impressionism, Post-Impressionism and Cubism. All three helped realize the idea that art could be non-representative.

Modern abstract art was born early in the 20th century. It was completely radical for its day. Artists began to create simplified objections with little or no reference to the “real” world.