A controlling method of a display apparatus, comprising: in response to receiving a user voice, transmitting the user voice to a first server and receiving, from the first server, text information corresponding to the user voice; transmitting the received text information to a second server and receiving, from the second server, response information corresponding to the text information from the second server, wherein the response information is related to a control command; outputting a system response corresponding to the response information received from the second server, the system response including a user interface, UI screen; outputting a voice command guide including a sample sentence corresponding to a voice command which is applicable to a current situation of the display apparatus from among a plurality of pre-stored sample sentences corresponding to voice commands applicable to each display situation of the display apparatus, wherein the voice command included in the voice command guide is related to a specific operation that can be performed by voice control in the current situation of the display apparatus according to the outputted system response, wherein the voice command guide is displayed separately to the UI screen of the system response; receiving a user voice according to the voice command guide; and performing a function corresponding to the user voice, wherein the current situation includes at least one of a first situation in which the display apparatus displays a broadcast program received through a tuner and a second situation in which the display apparatus executes an application, the application being different to the broadcast program, wherein the outputting a voice command guide includes displaying a first voice command guide applicable to the first situation in the first situation and displaying a second voice command guide applicable to the second situation in the second situation, and wherein the first voice command guide and the second voice command guide are different from each other. in response to receiving a user voice, transmitting the user voice to a first server and receiving, from the first server, text information corresponding to the user voice; transmitting the received text information to a second server and receiving, from the second server, response information corresponding to the text information from the second server, wherein the response information is related to a control command; outputting a system response corresponding to the response information received from the second server, the system response including a user interface, UI screen; outputting a voice command guide including a sample sentence corresponding to a voice command which is applicable to a current situation of the display apparatus from among a plurality of pre-stored sample sentences corresponding to voice commands applicable to each display situation of the display apparatus, wherein the voice command included in the voice command guide is related to a specific operation that can be performed by voice control in the current situation of the display apparatus according to the outputted system response, wherein the voice command guide is displayed separately to the UI screen of the system response; receiving a user voice according to the voice command guide; and performing a function corresponding to the user voice, wherein the current situation includes at least one of a first situation in which the display apparatus displays a broadcast program received through a tuner and a second situation in which the display apparatus executes an application, the application being different to the broadcast program, wherein the outputting a voice command guide includes displaying a first voice command guide applicable to the first situation in the first situation and displaying a second voice command guide applicable to the second situation in the second situation, and wherein the first voice command guide and the second voice command guide are different from each other.