An air curtain is a device used to create a barrier of air across an opening, such as a doorway or window, to separate two different environments while allowing easy passage for people and objects. It works by blowing a controlled stream of air vertically downward, which forms an invisible barrier that helps prevent the exchange of air, dust, insects, and odors between the two spaces. Air curtains are commonly used in commercial and industrial settings to maintain indoor temperatures, improve energy efficiency, and enhance comfort. They are also utilized in food service establishments to help maintain sanitary conditions by preventing the entry of pests and airborne contaminants.