An advertisement generation system presents a time-dependent advertisement to a user based upon to a search term of a search query during a period of time via a communication network The system includes a search engine coupled to a web server for receiving the search query and for presenting a search results page. The search results page is accompanied with an immediate advertisement. In one embodiment, the system includes an advertisement repository to store data representing a plurality of advertisements and includes the immediate advertisement and the time-dependent advertisement. Also, the system includes a user profiler configured to communicate a plurality of search characteristics and includes a data structure to store the search characteristics. Lastly, an advertisement server is included to provide to the web server the immediate advertisement with an associated search results page and the time-dependent advertisement with a web page presented after the display of the search results page, until a period of time expires.