Twitter is a free social networking and micro-blogging service that enables its users to send and read messages known as tweets. Tweets are text-based posts of up to 140 characters displayed on the author's profile page and delivered to the author's subscribers who are known as followers. Senders can restrict delivery to those in their circle of friends or, by default, allow open access. Users can send and receive tweets via the Twitter website, Short Message Service (SMS) or external applications. While the service, itself, costs nothing to use, accessing it through SMS may incur phone service provider fees.
Twitter has been mentioned twice on the show once on iSpeed Date (on which Sam informed the world about Carly's personal spit), and on iWon't Cancel The Show (on which Señor Gutierez tweeted about his incident with Sam). Spencer follows both iCarly and Señor Gutieres (the last one leaving Freddie wondering why would Spencer be following a foreign dignitary).