An interface is an English word meaning such as a contact, an interface, a contact surface, a bonding surface, an intermediary, a bridge or the like. In the field of IT, it means a place where two objects are connected / contacted, and a procedure and a contract specifying rules for exchanging information and signals between the two. “”Hardware interface”” “”Software interface”” “”User interface”” can be roughly divided into three. Hardware interface is a protocol for connecting a plurality of devices to communicate and defining the shape of the connector and the format of electric signals. Various interfaces exist depending on the application, such as data transmission inside the computer, data transmission of the computer and peripheral devices, communication between computers. The software interface defines procedures and formats for exchanging data between programs. In particular, the convention for calling and using the functions of OS, middleware, libraries, etc. from the outside is called API (Application Programming Interface). Although it can be thought that the file format and the like are included in the software interface in a broad sense, it usually refers to the API in many cases. The user interface (UI) defines a method in which information is displayed to a user by a computer, and conversely, a method for a user to input information, and many years have passed through character-based means (CUI: Character User Interface) has been used, graphical user interface (GUI: Graphical User Interface) that uses graphics, image display, mouse operation and so on has been widely used in response to computer performance improvement and popularization There.