Twitter co-founder Evan Williams has announced he is stepping down as CEO to focus on product strategy for the micro-blogging site.
Writing in a blog post, Williams (pictured) said the launch of the "new Twitter" led to a realisation. "I am most satisfied while pushing product direction. Building things in my passion, and I've never been more excited or optimistic about what we have to build," said Williams.
Current Twitter COO, Dick Costolo, will become the new CEO with immediate effect.
"When I insisted on bringing Dick into the COO role a year ago, I got a lot of questions from my board. But I knew Dick would be a strong complement to me, and this has proven to be the case," added Williams.
Since Williams became CEO two years ago the number of registered Twitter users has grown from two million to more than 165 million.
The micro-blogging firm is still seeking ways to maintain growth and generate revenue as competition in the social-networking market intensifies.