How search engines like Google understand the time?
If you ask google these series of questions, he can give you the correct answers.1-  who was the president of US in 2015? Google: Obama2- who was the president of US in 2016? Google: Obama3- who was the president of US in 2017? Google: Obama - Trump4- who was the president of US in 2018? Google: TrumpHow Google(search engines) understand these times to answer the correct questions?