Texto sobre a historia da cartografia the natural language text, which is often called unstructured data, I take a structured approach to writing this book. The next chapter will formally define the problem, which allows us to see a structure of the problem. From the definition, we will see the key tasks of sentiment analysis. In the subsequent chapters, existing techniques for performing the tasks are described. Due to my research, consulting, and start-up experiences, the book not only discusses key research concepts but also looks at the technology from an application point of view in order to help practitioners in the field. However, I must apologize that when I talk about industrial systems, I cannot reveal the names of companies or their systems, partially because of my consulting/business agreements and partially because of the fact that the sentiment analysis market moves rapidly and the companies that I know of may have changed or improved their algorithms when you read this book. I do not want to create problems for them and for me.