The company founded in 2006 by Jack Dorsey, Biz Stone, and Evan Williams was Twitter.
Twitter emerged from Odeo, a podcasting company, after a brainstorming session about using short text messages to communicate with groups. Jack Dorsey developed the initial concept, and work began in early 2006. Dorsey posted the service’s first message, “just setting up my twttr,” on March 21, 2006; the public version launched in July.
The founding story is slightly more complicated than the question suggests. Noah Glass was also a key co-founder and helped shape the project, although his role was later minimized in some public accounts. Biz Stone and Evan Williams joined the effort through Odeo, and the group later formed Obvious Corporation to acquire the service and related assets.
Twitter initially emphasized brief, SMS-style status updates. Its familiar 140-character limit reflected early text-message constraints before later expansion. The company became publicly traded in 2013, was acquired by Elon Musk in 2022, and was merged into X Corp. in 2023, but Twitter remains the canonical answer for the company created in 2006.