14. A non-transitory computer readable storage medium having embodied thereon a program, the program being executable by a processor for performing a method comprising: receiving, by a social networking computer system, an advertisement request from an advertiser to advertise using a social networking system; identifying an indication in the advertisement request of an action on an object, the action selectable by the advertiser from a plurality of actions on objects provided to the advertiser by the social networking computer system; identifying an indication in the advertisement request for providing a message to a viewing user that another user connected to the viewing user in the social networking system has performed the indicated action; determining, by the social networking computer system, that the identified action was taken on the object by another user connected to the viewing user; receiving, at the social networking computer system from a client device of the viewing user, a request for social networking information to be displayed in a web page that is within a domain of an external system that is different from a domain of the social networking system; selecting, by the social networking computer system, a story for the viewing user for display on the client device as a social advertisement, wherein: the story is sponsored by an advertiser and is based on the advertisement request received by the social networking computer system, and the story comprises information about the identified action taken on the object by the other user; and sending, by the social networking computer system, the social advertisement to the client device for display in the interface of the page of the web page of the external system.
14. A non-transitory computer readable storage medium having embodied thereon a program, the program being executable by a processor for performing a method comprising: receiving, by a social networking computer system, an advertisement request from an advertiser to advertise using a social networking system; identifying an indication in the advertisement request of an action on an object, the action selectable by the advertiser from a plurality of actions on objects provided to the advertiser by the social networking computer system; identifying an indication in the advertisement request for providing a message to a viewing user that another user connected to the viewing user in the social networking system has performed the indicated action; determining, by the social networking computer system, that the identified action was taken on the object by another user connected to the viewing user; receiving, at the social networking computer system from a client device of the viewing user, a request for social networking information to be displayed in a web page that is within a domain of an external system that is different from a domain of the social networking system; selecting, by the social networking computer system, a story for the viewing user for display on the client device as a social advertisement, wherein: the story is sponsored by an advertiser and is based on the advertisement request received by the social networking computer system, and the story comprises information about the identified action taken on the object by the other user; and sending, by the social networking computer system, the social advertisement to the client device for display in the interface of the page of the web page of the external system. 21. The computer readable storage medium of claim 14 , wherein sponsorship of the story selected for display as a social advertisement maximizes the chance that the story will be provided for display to the viewing user in a situation where the story might not otherwise be selected for display.