Spoken language is the prime human tool for expressing meaning – "human" because spoken language seems to be a feature unique to homo sapiens sapiens; "prime" because speech has been around a lot longer than writing, which was invented as a way of representing speech; and finally, a "tool" because language serves to link meaning with expression. How language does this is one of the key questions answered in this book.

Given our shared capacity for language, it's hardly surprising that language represents a topic of interest to many human beings. Language is talked about using everyday words in everyday situations. But, as with any other discipline, linguistics has its own conventions for talking about the object of its inquiry, so that findings and insights can be shared clearly, concisely and without ambiguity. The language of language explored in this book refers to linguistics, the science of language, and linguists' agreed-upon ways of talking about the object of their investigation. What's interesting about linguistics is that language is both the object of exploration and the vehicle for expressing discoveries about language, much as the brain is both the object of investigation and the vehicle for studying itself, in the brain sciences.