What was the Hummingbird update?

The "Hummingbird" update was the first major update to Google's search algorithm since the 2010 "Caffeine" search architecture upgrade, but even that was limited primarily to improving the indexing of information rather than sorting through information.

Hummingbird is about synonyms but also about context. Google always had synonyms, but with Hummingbird it is also able to judge context - thereby judging the intent of a person carrying out a search, to determine what they are trying to find out.