An important part of our information-gathering behavior has always been to find out what other people
think. With the growing availability and popularity of opinion-rich resources such as online review sites and
personal blogs, new opportunities and challenges arise as people now can, and do, actively use information
technologies to seek out and understand the opinions of others. The sudden eruption of activity in the area of
opinion mining and sentiment analysis, which deals with the computational treatment of opinion, sentiment,
and subjectivity in text, has thus occurred at least in part as a direct response to the surge of interest in new
systems that deal directly with opinions as a first-class object.