Google has quietly retooled the closely guarded formula running its internet search engine to give better answers to the increasingly complex questions posed by web surfers.

The overhaul came as part of an update called "Hummingbird" that Google has gradually rolled out in the past month without disclosing the modifications.

Searching for answers: Amit Singhal, senior vice president of search at Google, introduces the new 'Hummingbird' search algorithm.

Google is trying to keep pace with the evolution of internet usage. As search queries get more complicated, traditional 'Boolean' or keyword-based systems begin deteriorating because of the need to match concepts and meanings in addition to words.

Hummingbird is the company's effort to match the meaning of queries with that of documents on the internet, said Amit Singhal, a company vice president