Public art is art in any media that has been planned and executed with the intention of being staged in the physical public domain, usually outside and accessible to all. Public art is significant within the art world, amongst curators, commissioning bodies and practitioners of public art, to whom it signifies a working practice of site specificity, community involvement and collaboration. Public art may include any art which is exhibited in a public space including publicly accessible buildings, but often it is not that simple. Rather, the relationship between the content and audience, what the art is saying and to whom, is just as important if not more important than its physical location.

Cher Krause Knight states, "art's publicness rests in the quality and impact of its exchange with audiences … at its most public, art extends opportunities for community engagement but cannot demand particular conclusion”, it introduces social ideas but leaves room for the public to come to their own conclusions. In recent years, public art has increasingly begun to expand in scope and application — both into other wider and challenging areas of art-form, and also across a much broader range of what might be called our 'public realm'. Such cultural interventions have often been realised in response to creatively engaging a community's sense of 'place' or 'well-being' in society.

Such commissions can still result in physical, permanent artworks and sculptures. These also often involve increasingly integrated and applied arts type applications. However, they are also beginning to include other, much more process-driven and action-research based artistic practices as well. As such, these do not always rely on the production of a physical or permanent artwork at all (though they still often do of course). This expanded scope of public art can embrace many diverse practices and art-forms. These might be implemented as stand-alone, or as collaborative hybrids involving a multi-disciplinary approach. The range of its potential is of course endless, ever-changing, and subject to continual debate and differences of opinion among artists, funders, curators, and commissioning clients.

Monuments, memorials and civic statuary are perhaps the oldest and most obvious form of officially sanctioned public art, although it could be said that architectural sculpture and even architecture itself is more widespread and fulfils the definition of public art. Increasingly most aspects of the built environment are seen as legitimate candidates for consideration as, or location for, public art, including, street furniture, street lighting, Lock On sculptures and graffiti. Public art is not confined to physical objects; dance, procession, street theatre and even poetry have proponents that specialise in public art.

Sculpture intended as public art is often constructed of durable, easily cared-for material, to avoid the worst effects of the elements and vandalism; however, many works are intended to have only a temporary existence and are made of more ephemeral materials. Permanent works are sometimes integrated with architecture and landscaping in the creation or renovation of buildings and sites,an especially important example being the programme developed in the new city of Milton Keynes, England.

Some artists working in this discipline use the freedom afforded by an outdoor site to create very large works that would be unfeasible in a gallery, for instance Richard Long's three-week walk, entitled "The Path is the Place in the Line". In a similar example, sculptor Gar Waterman created a giant arch measuring 35x37x3 feet which straddled a city street in New Haven, Connecticut. Amongst the works of the last thirty years that have met greatest critical and popular acclaim are pieces by Christo, Robert Smithson, Andy Goldsworthy, James Turrell and Antony Gormley, whose artwork reacts to or incorporates its environment.

Artists making public art range from the greatest masters such as Michelangelo, Pablo Picasso, and Joan Miró, to those who specialise in public art such as Claes Oldenburg and Pierre Granche, to anonymous artists who make surreptitious interventions.

In Cape Town, South Africa, Africa Centre presents the Infecting the City Public Art Festival. Its curatorial mandate is to create a week-long platform for public art - whether it be visual or performative artworks, or artistic interventions - that shake up the city spaces and allows the city's users to view the cityscapes in new and memorable ways. The Infecting the City Festival believes that public art should to be freely accessible to everybody in a public space.