1. A system configured to serve base content and relevant content to a user system based on an association of a user profile and the relevant content, such that the relevant content is relevant to a user, the system comprising: a plurality of web servers configured to serve the base content and the relevant content to the user system; a set of additional-content servers configured to serve the relevant content to the web servers if units in the user profile match units associated with the relevant content; a parsing server configured to extract the units in the user profile from the base content requested by the user and generate a ranked list of the units in the user profile; and a unit-matching module configured to determine whether the units in the user profile match units associated with the relevant content if the user requests the base content, wherein the web servers are configured to serve the base content and the relevant content if the units in the user profile match units associated with the relevant content.