Linguistics is a large field, or set of fields, involving the scientific study of language. At the interface between the sciences and humanities, linguistics is a battleground for anthropologists, philosophers, philologists, poets, theologians, psychologists, biologists, and neurologists, all of whom seek to describe language and how it works from their own perspective. The ever-receding and highly ambitious goal is a theory of how all aspects of language work.
Linguistics has many sub-fields. This includes comparative linguistics (which compares languages to each other), historical linguistics (history of language), and applied linguistics (putting linguistic theories to practical use). As a whole, linguistics concerns itself with three major problems: how we learn languages, how languages vary, and what is universal to language. Serious progress has been made on these questions during the 20th century, but there is still much more to investigate. Language is probably the most complex form of human behavior.
Many of the sub-fields of linguistics are arranged on a spectrum from concrete form to abstract meaning. Ranging from concrete to abstract, these include phonetics (the physical properties of speaking and listening), phonology (the study of specific sounds that make up words), morphology (the study of word structures and variations), syntax (how words are arranged into sentences), semantics (the meaning of words), pragmatics (how sentences are used to communicate messages in specific contexts), and discourse analysis (the highest level of analysis, looking at texts). Many students gain some exposure to these concepts as early as elementary school, but delving deeply into them tends to be a job for language majors or linguists.
Linguistic theories have many large holes which need to be filled, but possibly one of the most interesting is the question of the origin of language: we have little idea when it was. It could been as long as 2.2 million years ago, with early members of the genus Homo, like Homo habilis, or as recently as 200,000 years ago, when modern humans evolved in Africa. Because spoken language leaves no artifacts, analysis of early language use circumstantial evidence like tool complexity. Based on anatomical studies, many scientists suspect that Neanderthals had some rudimentary form of language, and crude reconstructions of Neanderthals pronouncing vowel noises have been synthesized in computers.