Twitter's CEO Evan Williams is stepping down and handing his torch over to Chief Operating Officer, Dick Costolo.

Williams said he will stay involved in "product strategy", while the new CEO, Costolo takes charge of various monetization efforts Twitter has launched in the past few months - most of them focusing on providing marketing and advertising services.

During his run as CEO, Twitter grew from around 20 employees to 300, the number of tweets exploded from 1.25 million daily to 90 million, registered users also saw the same explosion in numbers going from 3 million to more than 160 million.

Considering Twitter was created as a "side project" in 2006 - it has come a very long way in the past 4 years.