Subjectivity and sentiment analysis: An overview of the current state of the area and envisaged developments

In this introduction, we present an overview of the current state of research in the Natural Language Processing tasks of subjectivity and sentiment analysis, as well as their application domains and closely-related research field of emotion detection. Although many definitions exist for these tasks and the research done within their frame spans over approaches with different objectives, we consider subjectivity analysis to deal with the detection of “private states” (opinions, emotions, sentiments, beliefs, speculations) and sentiment analysis as the task of detecting, extracting and classifying opinions and sentiments concerning different topics, as expressed in textual input. After describing the key concepts and research directions in these tasks, we present the main achievements obtained so far and the issues that remain to be tackled. Subsequently, we introduce each of the papers in this volume and present their contribution to the research areas of subjectivity and sentiment analysis. Finally, we conclude on the present state of work in these fields and reflect on the possible future developments.