Abstract: An apparatus for identifying a client accessing a first network site utilizes a control site to maintain information relating to the client. To that end, in response to receipt of a request from the client to access the first network site, it is determined if the client includes a first site data block. If it is determined that the client does not include the first site data block, then the control site is controlled to produce a control site data block having both control site identification data and a client identifier. The control site data block then is transmitted from the control site to the client In a similar manner, the client identifier is transmitted from the control site to the first network site. Upon receipt of the client identifier by the first network site, the first network site is controlled to transmit the first site data block to the client. The first site data block may have both the client identifier and first site identification data.