1 A method for providing advertisements in a web page, comprising: receiving a first set of one or more advertisements for display on a web page; providing the first set of one or more advertisements to be displayed on the web page; receiving at least one event notification indicating a modification to a context of the web page; generating a second request for one or more advertisements for display on the web page based on the at least one event notification; receiving a second set of one or more advertisements; and providing the second set of one or more advertisements to be displayed on the web page in place of at least one advertisement of the first set.