Google co-founders Sergey Brin and Larry Page are stepping down from their roles as president and CEO, respectively, of Alphabet (NASDAQ:GOOGL) (NASDAQ:GOOG), the technology colossus they helped create.

In their place will step Sundar Pichai, who has served as Google's CEO since August 2015. He will continue in that role while also becoming CEO of Alphabet, the parent holding company of Google that was formed in October 2015 to oversee a collection of early stage investments known as "other bets."

An empty boardroom with a large window showing tall buildings.

New Alphabet CEO Sundar Pichai has some big shoes to fill. Image source: Getty Images.

In a letter, Brin and Page wrote:

With Alphabet now well-established, and Google and the Other Bets operating effectively as independent companies, it's the natural time to simplify our management structure. We've never been ones to hold on to management roles when we think there's a better way to run the company. And Alphabet and Google no longer need two CEOs and a President. Going forward, Sundar will be the CEO of both Google and Alphabet. He will be the executive responsible and accountable for leading Google, and managing Alphabet's investment in our portfolio of Other Bets.

Alphabet's "other bets" segment includes Waymo, a self-driving car business that some analysts believe could eventually be worth $100 billion. They also include commercial drone delivery company Wing, healthcare-focused businesses Verily and Calico, and several other high-tech start-ups.

Yet despite the sizable investments Alphabet has devoted to these "other bets," Google continues to generate nearly all of its parent company's revenue and profits. Thus, Pichai was the clear choice to lead Alphabet. In their letter, Page and Brin wrote:

Sundar brings humility and a deep passion for technology to our users, partners and our employees every day. He's worked closely with us for 15 years, through the formation of Alphabet, as CEO of Google, and a member of the Alphabet Board of Directors. He shares our confidence in the value of the Alphabet structure, and the ability it provides us to tackle big challenges through technology. There is no one that we have relied on more since Alphabet was founded, and no better person to lead Google and Alphabet into the future.

Notably, Page and Brin will "remain active as co-founders, shareholders and board members of Alphabet." Although Alphabet should be in good hands with Pichai at the helm, Page and Brin's continued guidance is likely to comfort employees and investors alike.

"It's impossible to overstate Larry and Sergey's contributions over the past 21 years," Alphabet Board Chairman John Hennessy said in a press release. "I'm grateful that they will continue their involvement on the Board."

Looking back, it's amazing what Page, Brin, and their team have accomplished over the past two decades. From its humble beginnings, Google, now Alphabet, has grown into one of the world's most powerful businesses with multiple products that are used by more than a billion people every day.

"We are deeply humbled to have seen a small research project develop into a source of knowledge and empowerment for billions -- a bet we made as two Stanford students that led to a multitude of other technology bets," Page and Brin wrote. "We could not have imagined, back in 1998 when we moved our servers from a dorm room to a garage, the journey that would follow."

Looking forward, Alphabet's future remains bright. In fact, the company's biggest achievements may still lie ahead.

"We have a timeless mission, enduring values, and a culture of collaboration and exploration," Pichai said. "It's a strong foundation on which we will continue to build."