The sculptor Alexander Calder is well known for his mobiles. Calder invented the mobile in 1931. Marcel Duchamp suggested the name "mobile". Mobiles are also popular in the nursery, where they hang over cribs to give infants something to entertain them and give them external visual stimulation.The meaning of the term “mobile” as applied to sculpture has evolved since it was first suggested by Marcel Duchamp in 1931 to describe the early, mechanized creations of Alexander Calder. At this point, “mobile” was synonymous with the term “kinetic art”, describing sculptural works in which motion is a defining property. While motor or crank-driven moving sculptures may have initially prompted it, the word “mobile” later came to refer more specifically to Calder’s free-moving creations. Influenced by the abstract work of Piet Mondrian, Joan Miró and Sophie Taeuber-Arp, Calder in many respects invented an art form where objects (typically brightly coloured, abstract shapes fashioned from sheet metal) are connected by wire much like a balance scale. By the sequential attachment of additional objects, the final creation consists of many balanced parts joined by lengths of wire whose individual elements are capable of moving independently or as a whole when prompted by air movement or direct contact. Thus, “mobile” has become a more well-defined term referring to the many such hanging constructs Calder produced in a prolific manner between the 1930s and his death in 1976. A succinct definition of the term “mobile” in a visual art sense could be a type of kinetic sculpture in which an ensemble of balanced parts capable of motion are hung freely in space.