Twitter is an online news and social networking service where users post and interact with messages, "tweets," restricted to 140 characters. Registered users can post tweets, but those who are unregistered can only read them. In the past few years, there has been a huge growth in the use of microblogged platforms such as Twitter. Spur by that growth, companies and media organizations are increasingly seeking ways to mine Twitter for information about what people think and feel about their products and services. Many times, these companies study user reactions and reply to users on microblogs. One challenge is to build technology to detect and summarize an overall sentiment