SAN FRANCISCO — Larry Page and Sergey Brin, the Stanford graduate students who founded Google over two decades ago, are stepping down from executive roles at Google’s parent company, Alphabet, they announced on Tuesday.

Sundar Pichai, Google’s chief executive, will become the chief of both Google and Alphabet.

The move is an end of an era for Google. Mr. Page and Mr. Brin have personified the company since its founding and have been two of the technology industry’s most influential figures, on a par with the founders of Apple and Microsoft, Steve Jobs and Bill Gates.

Their early work on the Google search engine helped corral an unruly cloud of information on the World Wide Web. And their ideas about how to run an internet company — like offering generous employee perks like free shuttle buses to the office and making rank-and-file employees feel as though they have a stake in the company — became a standard for Silicon Valley.

Mr. Page and Mr. Brin took lesser roles in day-to-day operations in 2015 when they turned Google into Alphabet, a holding company that includes the self-driving car company Waymo under its umbrella.