The history of modern art is less a timeline than a
sequence of ideas. The "modern" period in art is less distinguished by beginning and ending dates than by the advent of a new approach.
The current modern era is widely considered to have begun in the late 1800's in
the arts and crafts guilds of England. Over the past 120 years or so, artisans, painters, sculptors, and various designers have advanced the "modern" concept of art.
"Modernism," more commonly, is used to describe a
philosophy of art, a foundation-level grounding that rejects practices of the past precisely because they are "of the past." It embraces the modern, rejecting, often out-of-hand, styles, concepts and techniques that
represent "old" ideas and ideals.
So the propellant of modern art is the appreciation for the new. Thus, the history of modern art is characterized by the constant invention of new means of expression. It is a history
of revolutions throwing over revolutions, movements supplanting movements, and the continual redefinition of artistic standards.
In many ways the modern art movement is not governed by artistic standards, but rather
by a political and competitive need to be "new." Consequently, the measure of quality is not artistic or aesthetic excellence, which would be measurements from an age of "the past." Rather, the measure of success for a
modern artist is the ability to push the creative envelope, to be the first to break a particular barrier.
In this respect, the history of modern art is a history of pushing boundaries, of testing the "edge" of
cultural, societal, and personal values, often by creating art that goes beyond those boundaries. As the inherent value for "pushing the envelope" has spread to new visual media (television, film, and now digital), this
appreciation for the "new" can be seen in program themes and content, as well as standards for quality.