Display apparatus, control method thereof and display system of the same

A display apparatus, a control method thereof and a display system of the same are provided to enable a user who has a control right to share data among plural users without a sever. A first controller determines whether to share data with a second display device(S1). If so, the first controller loads the data to be shared to a first memory unit(S3) and transmits the data to the second display device(S5). If a user changes data(S9), the first controller transfers address information of reference address to which the data are loaded and data change information(S11).