1. A memory device having instructions stored thereon that, in response to execution by a processing device, cause the processing device to perform operations comprising: identifying a key phrase that appears in digital content; generating a score for the key phrase based at least in part on social media popularity of the key phrase and frequency of the key phrase on a peer group of digital pages associated with a target digital page of the digital content, the peer group of digital pages of a plurality of network accessible sites; identifying said peer group of digital pages, at least in part, by identifying at least one of an outbound link from or an inbound link to the target digital page; determining, based at least in part on the score, whether to use the key phrase to select contextually relevant content to associate with the digital content; and responsive to determining to use the key phrase to select contextually relevant content to associate with the digital document, storing an indication of the determination in the memory device or another memory device.