In social science, the term built environment refers to the human-made surroundings that provide the setting for human activity, ranging in scale from buildings and parks or green space to neighborhoods and cities that can often include their supporting infrastructure, such as water supply or energy networks. The built environment is a material, spatial and cultural product of human labor that combines physical elements and energy in forms for living, working and playing. It has been defined as "the human-made space in which people live, work, and recreate on a day-to-day basis." The "built environment encompasses places and spaces created or modified by people including buildings, parks, and transportation systems." In recent years, public health research has expanded the definition of "built environment" to include healthy food access, community gardens, "walkability" and "bikability."