Used in a broad sense, avant-garde refers to any trailblazing movement — usually artistic or social — led by a small group of people to open new doors within their realm of interest. Specifically, avant-garde refers to a moment within the art world which encompasses many schools and sub-movements.

While avant-garde originally was used to describe only cutting-edge movements, as time has progressed many movements have retained the label of avant-garde long after they have ceased to be novel or groundbreaking. Dadaism and modernism, for example, are both considered examples of avant-garde art — though both have been around for nearly a century. This has led many to label movements as historically avant-garde, stressing that in a contemporary setting they are no longer avant-garde forms of expression.

The term experimental is often used interchangeably with avant-garde, particularly when focusing on a specific area of artistic interest. Examples include experimental theatre and experimental film.

Attempts to specifically define and delineate what is and what is not avant-garde are necessarily problematic, since the definition is ultimately one of personal opinion. What seems cutting-edge and revolutionary to one group of critics may seem tame and overdone to another. While avant-garde schools such as Pop art and Fluxus have a fairly defined set of criteria for what makes a body of work belong to their school, avant-garde has no such dictates. Rather, a piece is considered avant-garde if it is avant-garde — a circular reasoning that causes a great deal of general confusion.

Some efforts have been made recently to define avant-garde more rigidly; these attempts set the criteria for an avant-garde piece to be primarily concerned with pushing the envelope with regards to the artistic experience. Works that exist primarily to make a political or social statement not focused on art, are not to be considered avant-garde.

A number of artists who are considered avant-garde have rejected the label entirely, most claiming it is more trouble than it is worth. It is perhaps ironic that the artists most likely to be considered avant-garde are those most opposed to confining labels — they desire to break free of boundaries and labels in their artistic expression.

Avant-garde is also sometimes used pejoratively, particularly when regarding a non-artistic sphere. Philosophical and scientific ideas, for example, may be dismissed as being avant-garde, indicating that they exist more as a token gesture to challenge standing theories and tradition than to present new substantiatied ideas.