SAN FRANCISCO: Twitter is designed to open a window into the lives of people who muse about their activities, opinions and other things important to them. Here, then, are insights into some of the key figures involved in Twitter's creation and evolution into a communications hub that is pulling off the biggest Internet IPO since Facebook went public nearly 18 months ago.

The initial public offering of stock was priced Wednesday evening at $26 a share, valuing the company at more than $18 billion. It will start trading Thursday under the ticker symbol "TWTR."

Jack Dorsey, co-founder and Chairman, (at)jack

It has been an incredible turn of events for a former punk rocker who used to wear a nose ring and once considered giving up computer programming to become a fashion designer. Here's a glimpse of what Dorsey looked like eight years ago in a picture taken by a co-worker:

Dorsey, 36, is so impeccably groomed now that he is considered among the best-dressed men in technology. If you follow him on Twitter, you will find he has an affinity for big cities, especially St. Louis, where he grew up. He likes to use Twitter's Vine app to post short clips of street scenes and his view from airplanes.

Dorsey's fascination with dispatch systems for cabs, emergency services and bike messengers inspired the idea for a real-time communications system that morphed into Twitter. Precisely how his idea turned into Twitter is a matter of dispute.

Whatever his role was, Dorsey has emerged as a Silicon Valley sensation as Twitter's chairman and as CEO of a mobile payment processor called Square. He is frequently touted as the next Steve Jobs, a comparison he hasn't tried to discourage while also positioning himself for a possible political career. He has said he would eventually like to be mayor of New York, where he once lived. He now resides in San Francisco.

Although Dorsey has been Twitter's chairman since 2008, his power has been limited by a concession he made when he relinquished the CEO job to Evan Williams that same year. As part of that change in command, Dorsey handed over the voting rights of his Twitter stock to Williams. Dorsey is regaining those rights as part of Twitter's IPO.

Noah Glass, co-founder, (at)noah

Glass was one of Twitter's early architects and even came up with the name, according to a new book that rehashes the company's origins. But his early role has been glossed over through the years, and exactly what he did is also a matter of dispute. His name isn't mentioned in the regulatory filings for Twitter's public stock offering.

Glass left San Francisco after his ouster from Twitter, but returned to the city two years ago, according to his Twitter feed. His Twitter profile proclaims with brevity, "I started this."

Glass, 43, is the father of a 7-month-old girl and lives with her mother in a small house in San Francisco, just a few blocks away from where Glass says he and Dorsey conceived Twitter.

In a 2006 blog post recalling how he helped start Twitter, Glass wrote that he relished "tackling problems that had never been solved before." It's not clear if he is working on anything new now because he didn't respond to requests for an interview.

Evan Williams, co-founder, (at)ev

A former Nebraska farm boy, Williams has been variously described as deliberate, indecisive, taciturn, brilliant and even unscrupulous by those who believe he shoved aside Dorsey and Glass to consolidate his power.

Williams, 41, emerged as Twitter's largest shareholder by seizing an opportunity that arose as his podcasting startup, Odeo, foundered. Odeo was formed in late 2004 with Glass, then Williams' neighbor. Odeo initially subsisted on some of the millions that Williams made when he sold an online blogging tool called Blogger to Google in 2003.

By early 2006, it became apparent even to Williams that Odeo was unlikely to survive, so he encouraged the company's engineers to start coming up with ideas. The brainstorming hatched Twitter. Its potential looked promising enough for Williams to buy it from Odeo's early investors through another company that he formed, Obvious Corp.

Williams replaced Dorsey as Twitter's CEO in October 2008 and then stepped aside himself two years later when he turned over the reins to Dick Costolo. Williams remains on Twitter's board. He is also trying to build another online communications service called Medium. That comes through Obvious, which remains Williams' company after Twitter broke away in 2007. If you follow him on Twitter, you'll notice he spends a lot of time mulling a wide variety of subjects while mixing in a dry sense of humor.

Biz Stone, co-founder, (at)biz

The self-described dork has a gift for gab that made him Twitter's most visible face while he worked the TV talk show circuit and handled most of the media during the company's early years.

His real first name is Christopher, but as a child he used to pronounce it "Biz-ah-bah," based on what he thought his father - an auto mechanic in Boston - was saying when he called to him in a thick New England accent. He uses his middle name "Isaac" on official paperwork because his father is also named Christopher, a name his mother didn't want to hear after his parents got divorced when he was a kid.

Stone, 39, moved from Boston to Silicon Valley a decade ago primarily to work at Google with Williams, whom Stone once hailed as "the only person to consistently help me get the most out of my own brain and abilities." In 2005, Stone followed Williams to Odeo and then helped arrange the deal that spun out Twitter in October 2006 so it could be bought by Obvious. Twitter became its own company in 2007. Stone left Twitter in 2011 to join Williams at Obvious.

Stone is now working on a startup called Jelly Industries, which is believed to be working a system that will answer questions posed on mobile devices. If you follow Stone on Twitter, you will learn he is a vegan, animal lover and an optimist "who believes in the triumph of humanity with a little help from technology."

Dick Costolo, CEO, (at)dickc

It took a joker to turn Twitter into a serious business. Although Twitter still hasn't made any money, at least its revenue is rising at an impressive clip - something that couldn't be said until Costolo joined the company as chief operating officer in 2009. Within a year, the former stand-up comic from Chicago had replaced Evan Williams as CEO.

When Costolo took charge in 2010, Twitter's revenue was $28 million. This year, it's on track to be more than $600 million. Yet Twitter's losses are also mounting, mainly because Costolo has been spending lots of money to prepare for what he hopes will be years of steady growth. The company has invested heavily in more data centers to ensure the service doesn't break down as frequently as it did in its youth. When Costolo took over, Twitter had about 100 workers; now the company employs 2,300 people.

This is the fourth company that Costolo has helped build since leaving the stage as a comic. The three previous startups that he helped found and run all were sold. That includes FeedBurner, which Google bought for about $100 million in 2007.

Costolo, 50, still unleashes one-liners at Twitter's weekly "Tea Time" sessions with employees. His wisecracks also surface in his Twitter posts, and one of them recently ruffled some feathers.

After The New York Times published a story in October highlighting the lack of women on Twitter's board of directors, Costolo likened one of the critics quoted in the piece to the cartoonish comedian Carrot Top. Twitter lit up with indignation over Costolo's remark, which brought even more attention to the criticism.