An online system, including a smart laundry machine, which is capable of easily and inexpensively using the smart laundry machine is disclosed. A further extended type of a smart home appliance, an online system including the same, and a method of using the online system are also disclosed. A method of using an online system includes transmitting user information to a server through an external terminal to log in to the server, the server specifying a home appliance for a remote service based on the user information received from the external terminal and determining whether remote service activation of the specified home appliance is set, upon determining that the remote service activation of the home appliance is set, the server transmitting operation information of the home appliance to the external terminal, the external terminal transmitting a command signal to the server such that the home appliance is operated based on the received operation information, the server receiving the command signal, and the server transmitting the command signal to the home appliance such that the home appliance is operated.