A system for identifying a same user of multiple communication devices is configured to perform the steps of: (a) receiving first data relating to a first device operated by a user; (b) receiving second data relating to a second device operated by a user; (c) determining that the user of the first device is the user of the second device based on identifying that the first data is substantially the same as the second data; and (d) selecting and transmitting a sponsored content to the second device for display thereon, wherein the sponsored content has a relevance to the first and second data and/or a user characteristic datum associated with the user.