Google humming bird is launched to improve the quaility of Search results. According to Humming bird update your website must contain the high quality and informative content.Those website having poor content humming bird affects their ranking.
Essentially, (from what I'm understanding), is that Google is paying closer attention to the keywords in the search phrase. For example, (taken from the Register UK article) you type in: "butter vs olive oil" and you'll come up with a comparison of cholesterol, calories, and such. Does this help you?
Google suggested that the "Hummingbird" update rolled out about a month earlier. Our best guess ties it to a MozCast spike on August 20th and many reports of flux from August 20-22. Hummingbird has been compared to Caffeine, and seems to be a core algorithm update that may power changes to semantic search and the Knowledge Graph for months to come. @moz