Seamless is an English word meaningless, seamless, seamless, and so on. When a plurality of elements are joined together, it means that the joint does not exist or can not be recognized, which is not a concern. In the field of IT, when services, systems, software, etc. are composed of a plurality of elements or a combination of a plurality of different providers, from the viewpoint of the user, the difference is not recognized and consciously used unity It is said that it is seamless that you can do it. It is seamless that it is not necessary for users to be conscious of the proper use by automatically switching process etc. when it is necessary to select and switch multiple elements depending on the situation. Automatic switching between Wi-Fi connection and mobile data communication service on a smartphone, etc. It is also seamless to be able to use the same service and software from different kinds of equipment and to be able to receive the same service at various windows and facilities.