Sophie Calle is a French writer, photographer, installation artist, and conceptual artist. Calle's work is distinguished by its use of arbitrary sets of constraints, and evokes the French literary movement of the 1960s known as Oulipo. Her work frequently depicts human vulnerability, and examines identity and intimacy. She is recognized for her detective-like ability to follow strangers and investigate their private lives. Her photographic work often includes panels of text of her own writing.