Application interfaces allow two software applications to communicate and transfer data between each other. There are three main types of application interfaces: manual, automated/scheduled, and on-demand/event-driven. Manual interfaces involve manually exporting data from one application and importing it into another. Automated interfaces use scheduled exports and imports, often daily. On-demand interfaces can transfer data in real-time using web services. Recently, more requests are for on-demand interfaces while automated interfaces remain most common. An industry group also developed standards to facilitate integration between multifamily housing applications.