Jack Patrick Dorsey (born November 19, 1976) is an American Internet entrepreneur and programmer who is a co-founder and former CEO of Twitter, Inc., as well as co-founder, principal executive officer and chairperson of Block, Inc., the developer of the Square financial services platform. Dorsey was born and raised in St. Louis, Missouri, the son of Tim and Marcia (née Smith) Dorsey. He is of part-Italian descent on his mother's side. His father worked for a company that developed mass spectrometers and his mother was a homemaker. He was raised Catholic, and his uncle is a Catholic priest in Cincinnati. Dorsey attended Bishop DuBourg High School. In his younger days, he worked occasionally as a fashion model. By age 14, he had become interested in dispatch routing. Dorsey enrolled at the University of Missouri–Rolla in 1995 and attended for two-plus years before transferring to New York University in 1997, but he dropped out two years later, one semester short of graduating. He came up with the idea that eventually became Twitter while studying at NYU. While working on dispatching as a programmer, Dorsey moved to California. In 2000, Dorsey started his company in Oakland to dispatch couriers, taxis, and emergency services from the Web. His other projects and ideas at this time included networks of medical devices and a "frictionless service market". In July 2000, building on dispatching and inspired in part by LiveJournal and by AOL Instant Messenger, he had the idea for a Web-based realtime status/short message communication service. When he first saw implementations of instant messaging, Dorsey wondered whether the software's user status output could be shared easily among friends.He approached Odeo, which at the time happened to be interested in text messaging. Dorsey and Biz Stone decided that SMS text suited the status-message idea, and built a prototype of Twitter in about two weeks. The idea attracted many users at Odeo and investment from Evan Williams, a co-founder of that firm in 2005 who had left Google after selling Pyra Labs and Blogger. Dorsey, along with co-founder Jim McKelvey, developed a small business platform to accept debit and credit card payments on a mobile device called Square, released in May 2010. The small, square-shaped device attaches to iPhone, iPad, iPod Touch, or Android devices via the headphone jack, and as a mini card reader, allows a person to swipe their card, choose an amount to transfer to the recipient and then sign their name for confirmation. Square is also a system for sending paperless receipts via text message or email, and is available as a free app for iOS and Android OS. The company grew from 10 employees in December 2009 to over 100 by June 2011. Square's office is on Market Street in San Francisco. In September 2012, Business Insider magazine valued Square Inc. at US$3.2 billion. Dorsey is CEO of Square, Inc. On October 14, 2015, Square filed for an IPO to be listed on the New York Stock Exchange. As of that date, Dorsey owned 24.4 percent of the company. In March 2020 the FDIC permitted Square to open a bank. It announced plans to launch Square Financial Services in 2021. In May 2020, Dorsey announced that employees of Square would permanently become remote workers. In 2020, Square began withholding for months up to 30 percent of the funds that merchants collected from customers using its Cash App.[76] On December 1, 2021, CEO Jack Dorsey officially changed the name of the platform to Block, Inc. This was due in part to his interest in the blockchain as well as the new name encompassing the various businesses better than the current name, which is mostly associated with its merchant-payment services. The stock ticker for Block, Inc. would remain "SQ". Dorsey is a co-founder of Bluesky Social, a Twitter spin-off developing a decentralized social networking protocol and app.