INTELLIGENT FEATURE EXPANSION OF ONLINE TEXT ADS

Embodiments employ knowledge from network searches to enrich features useable to describe an advertisement. Advertisement content may be segmented to generate key phrases that are rank ordered based on a phrase's pointwise mutual information value with Ad keywords and term frequency-inverse document frequency (TF-IDF) scores. These key phrases are employed to generate a plurality of query searches that are performed to generate a plurality of search result snippets. The snippets are then analyzed and ranked to identify query expansion features having a TF-IDF value over a given threshold. A subset of these ranked phrases are combined with the Ad keywords to be used to rebuild an Ad index for the given advertisement. When content is to be delivered to a client device, content keywords are compared to the Ad index to select an advertisement to be provided with the content to the client device.