Twitter's origins lie in a "daylong brainstorming session" held by board members of the podcasting company Odeo. Dorsey introduced the idea of an individual using an SMS service to communicate with a small group. The original project code name for the service was twttr, an idea that Williams later ascribed to Noah Glass, inspired by Flickr and the five-character length of American SMS short codes. The developers initially considered "10958" as a short code, but later changed it to "40404" for "ease of use and memorability." Work on the project started on March 21, 2006, when Dorsey published the first Twitter message at 9:50 PM Pacific Standard Time (PST): "just setting up my twttr".
"...we came across the word 'twitter', and it was just perfect. The definition was 'a short burst of inconsequential information,' and 'chirps from birds'. And that's exactly what the product was." – Jack Dorsey
The first Twitter prototype was used as an internal service for Odeo employees and the full version was introduced publicly on July 15, 2006. In October 2006, Biz Stone, Evan Williams, Dorsey, and other members of Odeo formed Obvious Corporation and acquired Odeo and all of its assets – including Odeo.com and Twitter.com – from the investors and shareholders. Williams fired Glass who was silent about his part in Twitter's startup until 2011. Twitter spun off into its own company in April 2007.
The tipping point for Twitter's popularity was the 2007 South by Southwest Interactive (SXSWi) conference. During the event, Twitter usage increased from 20,000 tweets per day to 60,000. "The Twitter people cleverly placed two 60-inch plasma screens in the conference hallways, exclusively streaming Twitter messages," remarked Newsweek's Steven Levy. "Hundreds of conference-goers kept tabs on each other via constant twitters. Panelists and speakers mentioned the service, and the bloggers in attendance touted it."
Reaction at the conference was highly positive. Blogger Scott Beale said that Twitter "absolutely rul[ed]" SXSWi. Social software researcher danah boyd said Twitter "own[ed]" the conference. Twitter staff received the festival's Web Award prize with the remark "we'd like to thank you in 140 characters or less. And we just did!"