The term public art properly refers to works of art in any media that have been planned and executed with the specific intention of being sited or staged in the physical public domain, usually outside and accessible to all. The term is especially significant within the art world, amongst curators, commissioning bodies and practitioners of public art, to whom it signifies a particular working practice, often with implications of site specificity, community involvement and collaboration. The term is sometimes also applied to include any art which is exhibited in a public space including publicly accessible buildings.
In recent years, public art has increasingly begun to expand in scope and application — both into other wider and challenging areas of artform, 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.
From the Wikipedia article on Public Arts.