Jack Dorsey

Created Twitter to allow friends and family know what he was doing. The world’s fastest-growing communications medium let users broadcast their thoughts in 140 characters or less. No one thought people would want to follow strangers, or that celebrities would use Twitter to tell fans of their activities, or that businesses would use Twitter to announce discounts or launch new products.

His new company is Square, which turns cellphones into credit card readers.

Click on his name in the title to see his inspirational talk at Stanford in February 2011.

Dorsey's original design sketch for Twitter.









Read the Simple Twitter Book.