Start-Ups

Tech history in photos: Social media founders

Jack Dorsey, Twitter

Jack Dorsey is the co-creator and co-founder of Twitter. Twitter was one of the first "microblogging" services, and it taught the world to think in 140 characters or less.

Image: Wikimedia Commons/Joi Ito

By Conner Forrest

Conner Forrest is an analyst for 451 Research. He was formerly a Senior Editor for TechRepublic.