Abstract art uses a visual language of form, color and line to create a composition which may exist with a degree of independence from visual references in the world. Western art had been, from the Renaissance up to the middle of the 19th century, underpinned by the logic of perspective and an attempt to reproduce an illusion of visible reality.
Abstract art, nonfigurative art, nonobjective art, and nonrepresentational art are loosely related terms. They are similar, although perhaps not of identical meaning.
Abstraction indicates a departure from reality in depiction of imagery in art. This departure from accurate representation can be only slight, or it can be partial, or it can be complete. Artwork which takes liberties, altering for instance color and form in ways that are conspicuous, can be said to be partially abstract. Total abstraction bears no trace of any reference to anything recognizable. In geometric abstraction, for instance, one is unlikely to find references to naturalistic entities. Figurative art and total abstraction are almost mutually exclusive. But figurative and representational (or realistic) art often contains partial abstraction.
Both geometric abstraction and lyrical abstraction are often totally abstract. Among the very numerous art movements that embody partial abstraction would be for instance fauvism in which color is conspicuously and deliberately altered vis-a-vis reality, and cubism (See Picasso), which blatantly alters the forms of the real life entities depicted. (source Wikipedia)
2. Creating abstract art relies upon the perception of the artist. Abstract art reflects these perceptions instead of the actual objects, as is the case in traditional portrait or landscape painting. It stands alone from reality.