Linguistics is the science of language, including the sounds, words, and grammar rules. Word in language are finite, but sentences are not. It is this creative aspect of human language that sets is apart from animal language. The basic areas of study include phonology (the sound system), morphology (the structure of words), syntax (the combination of words into sentences), semantics (the ways in which sounds and meanings are related). Knowing a language encompasses this entire system, but this knowledge or competence is different from behavior or performance. We may know the language, but we may choose not to speak it. Although we are not speaking the language , we still have its knowledge. However, if we don,t know a language, we cannot speak it at all.