11. A non-transitory machine-readable medium storing instructions for execution by a computing apparatus, the instructions to perform operations comprising: receiving from a client device, a hyperlink to send to one or more users via a communication system to a communication system; acquiring a set of data from a target referenced by the hyperlink; storing at least a portion of the set of data on a server; analyzing the set of data to automatically generate a set of preview candidates for each of a summary and title of a preview for the hyperlink, ranking the preview candidates based on relevance to content at the target referenced by the hyperlink, wherein the relevance is determined via analysis of positive and negative signals for each candidate, and wherein the analysis includes a comparison of content from at least one title preview candidate with content from at least one summary preview candidate; selecting a top ranked summary and title from the set of candidates; and transmitting, to the client device, a preview candidate including the selected summary and title to the client device in response to receiving the hyperlink.
11. A non-transitory machine-readable medium storing instructions for execution by a computing apparatus, the instructions to perform operations comprising: receiving from a client device, a hyperlink to send to one or more users via a communication system to a communication system; acquiring a set of data from a target referenced by the hyperlink; storing at least a portion of the set of data on a server; analyzing the set of data to automatically generate a set of preview candidates for each of a summary and title of a preview for the hyperlink, ranking the preview candidates based on relevance to content at the target referenced by the hyperlink, wherein the relevance is determined via analysis of positive and negative signals for each candidate, and wherein the analysis includes a comparison of content from at least one title preview candidate with content from at least one summary preview candidate; selecting a top ranked summary and title from the set of candidates; and transmitting, to the client device, a preview candidate including the selected summary and title to the client device in response to receiving the hyperlink. 13. The non-transitory machine-readable medium of claim 11 further comprising identifying a content publisher referenced by the hyperlink and applying a set of content publisher preview generation rules to generate the one or more preview candidates.