12. A computer-implemented method for managing content for delivery over a network, the method comprising: providing a networked device comprising a memory and a processor configured to execute instructions stored in the memory; receiving, by the processor, an advertisement with Ad keywords associated with the advertisement; segmenting, by the processor, content of the advertisement into a plurality of phrases; performing, by the processor, a semantic analysis to the plurality of phrases; selecting, by the processor, top-ranked phrases from the plurality of phrases based on the semantic analysis to form a reduced subset of phrases; generating, by the processor, a query list having a plurality of queries by combining each phrase in the reduced subset of phrases that has less than a defined number of words with another independent phrase in the reduced subset of phrases to create queries comprising two or more words; for each query within the query list, performing, by the processor, an internet web search to identify a set of descriptions, each description describing a search result from the internet search; selecting, by the processor, a second set of phrases denoted as a query expansion feature set for each query based on an analysis of the set of descriptions; ranking, by the processor, the second set of phrases; generating, by the processor, an expanded Ad index by selecting from the ranked second set of phrases a subset of phrases as an ad expanded feature set that is combined with the Ad keywords associated with the advertisement; and when receiving a second content for display at a client device, selecting, by the processor, an advertisement from a plurality of advertisements, including the received advertisement, based on the expanded Ad index.
13. The computer-implemented method of claim 12 , wherein conducting the semantic analysis comprises: grouping related words from the content of the advertisement to generate a phrase from the content of the advertisement; determining a pointwise mutual information (PMI) value for each generated phrase with each Ad keyword; ranking in order the determined PMI values based on a Term Frequency-Inverse Document Frequency score for each generated phrase; and selecting from the rank ordering a subset of phrases as the reduced subset of phrases for the advertisement.