Opinions are central to almost all human activities and are key influencers of our behaviors. Our beliefs and perceptions of reality, and the choices we make, are, to a considerable degree, conditioned upon how others see and evaluate the world. For this reason, when we need to make a decision we often seek out the opinions of others. This is not only true for individuals but also true for organizations.
Opinions and its related concepts such as sentiments, evaluations, attitudes, and emotions are the subjects of study of sentiment analysis and opinion mining. The inception and rapid growth of the field coincide with those of the social media on the Web, e.g., reviews, forum discussions, blogs, microblogs, Twitter, and social networks, because for the first time in human history, we have a huge volume of opinionated data recorded in digital forms. Since early 2000, sentiment analysis has grown to be one of the most active research areas in natural language processing. It is also widely studied in data mining, Web mining, and text mining. In fact, it has spread from computer science to management sciences and social sciences due to its importance to business and society as a whole. In recent years, industrial activities surrounding sentiment analysis have also thrived. Numerous startups have emerged. Many large corporations have built their own inhouse capabilities. Sentiment analysis systems have found their applications in almost every business and social domain. The goal of this book is to give an in-depth introduction to this fascinating problem and to present a comprehensive survey of all important research topics and the latest developments in the field. As evidence of that, this book covers more than 400 references from all major conferences and journals. Although the field deals with the natural language text, which is often considered the unstructured data, this book takes a structured approach in introducing the problem with the aim of bridging the unstructured and
structured worlds and facilitating qualitative and quantitative analysis of
opinions. This is crucial for practical applications. In this book, I first define the problem in order to provide an abstraction or structure to the problem. From the abstraction, we will naturally see its key sub-problems. The subsequent chapters discuss the existing techniques for solving these subproblems.