What is Linguistics?

"At the heart of linguistics is the search for the unconscious knowledge that humans have about language(s), an understanding of the structure of language, and knowledge about how languages differ from each other."
(Linguistic Society of America)

"Languages are sets of signs. Signs combine an exponent (a sequence of letters or sounds) with a meaning. Grammars are ways to generate signs from more basic signs. Signs combine a form and a meaning, and they are identical with neither their exponent nor with their meaning."
(Introduction to Linguistics by M. Kracht, Dep. of Linguistics, UCLA (PDF))