A first terminal configured to operate in conjunction with a second terminal, the first terminal being further configured to operate in a data protection mode, and the first terminal comprising: a sensor configured to obtain information corresponding to a motion of the first terminal; a communicator configured to communicate with the second terminal; and a controller configured to: receive information corresponding to a motion of the second terminal from the second terminal via the communicator; determine a distance between the first terminal and the second terminal being greater than or equal to a critical value, based on a signal strength of a signal transmitted to the second terminal by the communicator or a signal strength of a signal from the second terminal received by the communicator; in response to the obtaining, receiving, and determining: control the communicator to transmit a notification message to the second terminal based on the information corresponding to the motion of the first terminal and the information corresponding to the motion of the second terminal; and control the first terminal to operate in the data protection mode. a sensor configured to obtain information corresponding to a motion of the first terminal; a communicator configured to communicate with the second terminal; and a controller configured to: receive information corresponding to a motion of the second terminal from the second terminal via the communicator; determine a distance between the first terminal and the second terminal being greater than or equal to a critical value, based on a signal strength of a signal transmitted to the second terminal by the communicator or a signal strength of a signal from the second terminal received by the communicator; in response to the obtaining, receiving, and determining: control the communicator to transmit a notification message to the second terminal based on the information corresponding to the motion of the first terminal and the information corresponding to the motion of the second terminal; and control the first terminal to operate in the data protection mode. receive information corresponding to a motion of the second terminal from the second terminal via the communicator; determine a distance between the first terminal and the second terminal being greater than or equal to a critical value, based on a signal strength of a signal transmitted to the second terminal by the communicator or a signal strength of a signal from the second terminal received by the communicator; in response to the obtaining, receiving, and determining: control the communicator to transmit a notification message to the second terminal based on the information corresponding to the motion of the first terminal and the information corresponding to the motion of the second terminal; and control the first terminal to operate in the data protection mode. control the communicator to transmit a notification message to the second terminal based on the information corresponding to the motion of the first terminal and the information corresponding to the motion of the second terminal; and control the first terminal to operate in the data protection mode.