Bio Box: Twitter co-founder hands off CEO job to chief operating officer, veteran entrepreneur

Bio Box: Twitter’s outgoing, incoming CEOs

NAME: Evan Williams

AGE: 38

TWITTER JOB: After spending the past two years as CEO, Williams will simply be known as “co-founder” and focus on product development.

TWITTER IDENTITY: (at)ev

BUSINESS BACKGROUND: Before helping to launch Twitter in 2006, Williams was best known as the founder of Blogger. He sold that blogging service to Google Inc. in 2003.

NAME: Dick Costolo

AGE: 47

TWITTER JOB: After spending the past year as Twitter’s chief operating officer, Costolo has been promoted to CEO.

TWITTER IDENTITY: (at)dickc

BUSINESS BACKGROUND: Costolo has cashed in on his entrepreneurial skills by selling an online ad service called FeedBurner to Google in 2007. He had previously started two other companies, SpyOnIt, which monitored Web pages, and Burning Door Networked Media, which helped design websites.