A method for updating the channel information of a search server, said search server being configured for: storing a channel map, whereby said channel map comprises a list of one or more items, ea ch item comprising a channel number, a source identifier ID, a channel name, and one or mor e alias, said source identifier ID being a unique channel identifier acquired from a broadcast signal, the alias including one or more channel names, and storing EPG information, and transmitting to a display apparatus a list of related contents retrieved by searching with a keyword corresponding to a channel name; the method comprising: receiving a channel number, a first source ID and a corresponding first channel name from one of a plurality of display apparatuses, searching for channel information, using said first source ID, wherein such searching comprises the steps of searching the channel map to check whether said first source ID and any of the source identifiers ID of the channel map are the same; and updating the channel information based on said searching, whereby: in response to the first source ID and any of the source identifiers ID of the channel map not being the same, adding the first source ID and the first channel name to the channel map; in response to the first source ID and a second source ID being the same, comparing the first channel name and the second channel name, and adding the first channel name to the alias in response to determining that the first channel name is different than the second channel name. storing a channel map, whereby said channel map comprises a list of one or more items, ea ch item comprising a channel number, a source identifier ID, a channel name, and one or mor e alias, said source identifier ID being a unique channel identifier acquired from a broadcast signal, the alias including one or more channel names, and said source identifier ID being a unique channel identifier acquired from a broadcast signal, the alias including one or more channel names, and storing EPG information, and transmitting to a display apparatus a list of related contents retrieved by searching with a keyword corresponding to a channel name; the method comprising: receiving a channel number, a first source ID and a corresponding first channel name from one of a plurality of display apparatuses, searching for channel information, using said first source ID, wherein such searching comprises the steps of searching the channel map to check whether said first source ID and any of the source identifiers ID of the channel map are the same; and updating the channel information based on said searching, whereby: in response to the first source ID and any of the source identifiers ID of the channel map not being the same, adding the first source ID and the first channel name to the channel map; in response to the first source ID and a second source ID being the same, comparing the first channel name and the second channel name, and adding the first channel name to the alias in response to determining that the first channel name is different than the second channel name. receiving a channel number, a first source ID and a corresponding first channel name from one of a plurality of display apparatuses, searching for channel information, using said first source ID, wherein such searching comprises the steps of searching the channel map to check whether said first source ID and any of the source identifiers ID of the channel map are the same; and updating the channel information based on said searching, whereby: in response to the first source ID and any of the source identifiers ID of the channel map not being the same, adding the first source ID and the first channel name to the channel map; in response to the first source ID and a second source ID being the same, comparing the first channel name and the second channel name, and adding the first channel name to the alias in response to determining that the first channel name is different than the second channel name. in response to the first source ID and any of the source identifiers ID of the channel map not being the same, adding the first source ID and the first channel name to the channel map; in response to the first source ID and a second source ID being the same, comparing the first channel name and the second channel name, and adding the first channel name to the alias in response to determining that the first channel name is different than the second channel name.