Art history is the historical study of human expression — tactile, visual, spatial, and even audible. Art historians use various tools and strategies to discover ways to transfer from the visible to the spoken through study and interpretations. Art historians develop a unique understanding and sensitivity of how material, visual, and – in contemporary art, often immaterial – expression creates purpose in the universe and how those ideas affect our political, social, and spiritual lives. Architectural historians study structures and their surroundings, the function of the community's built environment, and the link among people and their surroundings.