Twitter is an American online news and social networking service on which users post and interact with messages known as “tweets”. Tweets were originally restricted to 140 characters,this limit was doubled to 280 for all languages except Chinese, Japanese, and Korean. Registered users can post, like, and retweet tweets, but unregistered users can only read them. Users access Twitter through its website interface, through Short Message Service (SMS) or its mobile-device application software (“app”). Twitter places great reliance on open-source software. The Twitter Web interface uses the Ruby on Rails framework, deployed on a performance enhanced Ruby Enterprise Edition implementation of Ruby.