Alexander Calder was a renowned American artist who is best known for his mobiles artworks. He was born in 1898 and is often referred to as the 'father of the mobile'. His mobiles are sculptures that are composed of abstract shapes and objects that move freely in space. He was a pioneer in kinetic art, which is art that moves or changes over time. He created many large-scale public artworks, including the Stegosaurus in Pittsburgh, Pennsylvania. He died in 1976, but his work continues to be celebrated around the world.