Emotion and the emotions we study today have been discussed for centuries using words and phrases that reflect the thoughts of those times, but that have also become fossilised in modern Western thought. The concepts behind these expressions vary in content according to the context in which they are used, and their translations into other languages show that their usage, or that of their cognates, in each language allows for further different interpretations of the concepts, often influenced by the culture and society in which they are used. The studies of Emotion and Language are influenced by perspectives from the disciplines of philosophy, anthropology, psychology, sociology, neuroscience, and computer science, and cover not just the spoken or written form of the core concepts of emotion, but also descriptions of the expression of emotion through facial expression, body language, and physical reactions, and even subjective language in general. This article will attempt to provide a view of some of the issues that affect the understanding of the language of emotion, and that underlie many of the problems faced by those working in opinion mining, sentiment analysis, and human<>computer interaction. It will also touch on the complex relationship between emotion and cognition, and the problems this poses. The objective is to offer some interdisciplinary background for our second article, which presents a more detailed perspective from a computational point of view.