A display apparatus comprising: a display; a data processor configured to process content data to be displayed as a content image on the display; a user input interface configured to receive biometric information about a user; a communication interface configured to communicate with an external apparatus in use; and a controller configured to identify the user based on the biometric information received through the user input interface, and control the content data to be transmitted to and displayed as the content image on one between the display apparatus and the external apparatus, in which the user shows relatively high interest, if it is determined that the identified user is also a user of the external apparatus the display apparatus characterized in that: the interest in the display apparatus and the interest in the external apparatus are obtained by numerical values based on at least one of a position of the user's face and a direction of the user's pupil with respect to the display apparatus and the external apparatus, respectively; and the controller is configured to control both the display apparatus and the external apparatus to maintain the respective content images currently displayed based on both the interest by numerical value in the display apparatus and the interest by numerical value in the external apparatus being all higher than a preset first value or all lower than a preset second value, and select the one of the display apparatus and the external apparatus in which the interest by numerical value shows relatively high to display the content image. a display; a data processor configured to process content data to be displayed as a content image on the display; a user input interface configured to receive biometric information about a user; a communication interface configured to communicate with an external apparatus in use; and a controller configured to identify the user based on the biometric information received through the user input interface, and control the content data to be transmitted to and displayed as the content image on one between the display apparatus and the external apparatus, in which the user shows relatively high interest, if it is determined that the identified user is also a user of the external apparatus the display apparatus characterized in that: the interest in the display apparatus and the interest in the external apparatus are obtained by numerical values based on at least one of a position of the user's face and a direction of the user's pupil with respect to the display apparatus and the external apparatus, respectively; and the controller is configured to control both the display apparatus and the external apparatus to maintain the respective content images currently displayed based on both the interest by numerical value in the display apparatus and the interest by numerical value in the external apparatus being all higher than a preset first value or all lower than a preset second value, and select the one of the display apparatus and the external apparatus in which the interest by numerical value shows relatively high to display the content image. the interest in the display apparatus and the interest in the external apparatus are obtained by numerical values based on at least one of a position of the user's face and a direction of the user's pupil with respect to the display apparatus and the external apparatus, respectively; and the controller is configured to control both the display apparatus and the external apparatus to maintain the respective content images currently displayed based on both the interest by numerical value in the display apparatus and the interest by numerical value in the external apparatus being all higher than a preset first value or all lower than a preset second value, and select the one of the display apparatus and the external apparatus in which the interest by numerical value shows relatively high to display the content image. control both the display apparatus and the external apparatus to maintain the respective content images currently displayed based on both the interest by numerical value in the display apparatus and the interest by numerical value in the external apparatus being all higher than a preset first value or all lower than a preset second value, and select the one of the display apparatus and the external apparatus in which the interest by numerical value shows relatively high to display the content image.