1. A client computer system directly accessed by a user, the system comprising: a display; a gateway operable to connect the client computer system to a server; a local database, located on the client computer system and comprising at least preferences information of the user; and a processing module, located on the client computer system and operable to: i. obtain at least preferences information of the user by monitoring online activities of the user, wherein the preferences information of the user is based on a history of the online activities of the user on the Internet; ii. store the obtained preferences information of the user in the database; iii. receive a query from the user, the query identifying target information requested by the user; iv. after receiving the query, cause at least a portion of the received query to be transmitted to the server; v. receive information from the server, the received information being in response to the at least a portion of the query transmitted to the server; the received information comprising the target information requested by the user; vi. display to the user the target information requested by the user; vii. process the information received from the server; viii. determine likely preferences of the user based on contents of the database and the information received from the server in response to the at least a portion of the query transmitted to the server; ix. filter the information received from the server based on the likely preferences of the user; and x. cause the filtered information to be displayed to the user on the display, wherein the preferences information of the user is not accessible to any other entity except for the client computer system; wherein the server comprises a search engine, wherein the query is a search engine query and wherein the information received from the server comprises search results responsive to the query submitted by the user and a plurality of advertisements related to the search results, wherein the processing module is further operable to select at least one of the plurality of advertisements for displaying to the user based on the determined likely preferences of the user, wherein the selection is performed on the client computer system.
5. The client computer system of claim 1 , wherein the database further comprises user identity and demographic information and wherein the processing module is further operable to obtain the user identity and demographic information and store the obtained user identity and demographic information in the database.