"The story of English spelling is the story of thousands of people - some well-known, most totally unknown - who left a permanent linguistic fingerprint on our orthography." - David Crystal
Linguistics is simply defined as the study of language. Different aspects of linguistics are studied in varying ways depending on their background and usage. Some forms of linguistics help foreign-language teachers draw connections between their students' native and learned languages. Other types of linguistic studies assist anthropologists in understanding human cultures while still others aid cognitive scientists explain the human mind or help computer programmers reshape how we interact with technology.
Applied Linguistics
Applied linguistics uses linguistic theory to solve real-world problems, most often in the field of language education. For example, linguists can apply what they know about how children and adults learn languages to design educational materials and lessons for teaching second languages and to design effective methods of testing student progress. Educators can use what they know about how people actually use language to make sure their classes prepare students for the kinds of exchanges they are most likely to encounter.
Sociolinguistics
Sociolinguistics is a kind of linguistics closely tied to sociology, the study of groups of people. Sociolinguists investigate how languages function within populations in terms of both how language affects the population and how the population affects the language. Sociolinguists study how your time and place of origin and the social groups to which you belong affect the words you use and how you pronounce them.
Psycholinguistics
Psycholinguistics, closely tied to cognitive science, studies the relationship between language and the mind. Psycholinguists are interested in how the mind acquires and processes language. They look at both physical aspects of how words and syntax are stored and how and why they are called upon. Psycholinguists also look at the conceptual study of linguistics. Within their study, they also look at topics like how the mind acquires grammar, how language and thought are related, how language creates conceptual groups and how metaphors affect understanding.
Computational Linguistics
Computational linguistics uses computers to build models of languages. These models can be used to explain subtle patterns in a language's structure. The models are also used extensively in the computer industry to improve how we interact with technology by essentially teaching computers human languages. This allows them to read and reply to what we type and to hear us when we speak and to speak back. Computational linguistics is a driving force behind search engines, voice recognition, text-to-speech and artificial intelligence.