Linguistics is a general term for all disciplines of language research, and there are many branches within it, so the content of linguistics is very rich and colorful. This is mainly because the structure of language itself is very complicated, there are many kinds of languages, and language has many connections with human social life. People study languages with various purposes, angles and methods, thus forming various categories and schools of linguistics. Linguistics can be classified from various angles. Regarding the classification of linguistics, we should pay attention to the following classification angles: one is the function angle, the other is the research object, and the third is the classification from the time range of the research object. General linguistics mainly classifies from the perspective of function. From the functional point of view, linguistics can be divided into two categories: theoretical linguistics and applied linguistics. Here we introduce the classification from other angles. Due to different classification angles, a language subject can be divided into different categories. For example, modern Chinese belongs to theoretical linguistics in terms of function, idiomatic linguistics in terms of object and temporal linguistics in terms of research time. Linguistic categories are added to the syllabus, and several basic conceptual problems should be paid attention to in learning. (1) theoretical linguistics theoretical linguistics is the main part of linguistics and the theoretical basis of all linguistics. It includes the study of specific and individual languages and the study of various languages. According to different research objects, theoretical linguistics can be divided into two categories: general linguistics and specialized linguistics. 1. General Linguistics: Also called General Linguistics, it takes all human languages as the research object and is an important theoretical component of linguistics. It is based on people's research results of various specific languages and plays a guiding role in the research of specialized linguistics. It can be said that it is a comprehensive reflection and application of human language research results. The basic contents of general linguistics research include: the essence of language, the structure of language, the origin and development of language, the research methods of linguistics, and the position of linguistics in the discipline system. The nature of our course is general linguistics. General linguistics can be subdivided into general phonetics, general lexicology, general grammar and semantics. Our course belongs to general linguistics. 2. Professional linguistics: also known as concrete linguistics and personal linguistics. Professional linguistics provides rich materials for general linguistics. We should absorb the research results of applied general linguistics, accept the guidance of general linguistics, and promote and develop together with general linguistics. Idiom linguistics studies one or more languages. It can study specific languages, such as Chinese, which is called Chinese linguistics, and English, which is called English linguistics. We can also take several languages with kinship as the research object and analyze the characteristics of their development laws. For example, Zhuang language, Buyi language, Dai language and China local language are all kinship languages derived from the branch of Dong-Dai language, and the study of these languages is called Dong-Dai linguistics. English, German, Dutch, Swedish and Danish all come from Germanic languages, and the subject of studying them is called Germanic linguistics. Both ancient Chinese and modern Chinese that students have studied in junior college are specialized linguistics. The theory of general linguistics is based on the research results of specialized linguistics, and its development level depends on the research results of specific languages. The more research on specific languages, the richer the materials, and the more conducive to the development of general linguistic theory. At present, the research on specific languages is mainly limited to some big languages in the world, and there are still many languages, such as those of some remote and backward ethnic groups, which have not been well studied, and there may even be unknown languages. Therefore, the current theory of general linguistics only reflects part of the research results of language. With the deepening and expansion of linguists' research on various languages, linguistic theory will be further developed. Any language has its horizontal structure, relative stability, vertical development and history. To study analytical language, we should not only look at its contemporary state and understand its present situation, but also look at its development characteristics and find out the law of evolution. Therefore, specialized linguistics can study language from different angles, the development history of a language, and the situation of a language in a certain era. Accordingly, professional linguistics can be divided into diachronic linguistics and * * * temporal linguistics. (1) Diachronic linguistics: Studying the history of language development and observing the historical evolution of various structural elements of a language at different stages of development means studying the history of language from a vertical perspective. What involves a language is called historical linguistics, such as historical phonetics, historical lexicology, historical grammar and so on. Historical comparative linguistics involves many languages and dialects. (2)*** Temporal Linguistics: To study the relatively static state of language by synchronic static analysis, and to describe and analyze the state of language in a certain period and stage is to study language from a horizontal perspective. It can also be divided into descriptive linguistics and contrastive linguistics. Among them, descriptive linguistics is the most familiar one. It studies language in chronological order, and makes an objective, in-depth and detailed description and analysis of the language situation in a certain era to reflect the basic characteristics of this language. For example, modern Chinese, ancient Chinese and English grammar all belong to descriptive linguistics. It can also be divided into phonetics, lexicology, grammar, rhetoric and so on. Contrastive linguistics is a comparative study based on the description of several languages, aiming at finding out their similarities and differences. Although we don't study contrastive linguistics systematically, we should actually use the research results of contrastive linguistics to learn foreign languages, such as comparing the differences between English and Chinese in pronunciation, grammar and sentence structure. For example, English words vine and wine are the first phonemes to distinguish the meaning of words, while Chinese phoneme V does not have the function of distinguishing the meaning of W, such as "Wei, Wang, Wu, Wen and Wai". Reading w(u) as v does not affect the understanding of the meaning at all, and the listener will not care about your pronunciation here, which may be a bit strange for careful people. Of course, the division of * * * time and duration is mainly introduced in professional linguistics, but it should be noted that it is not only professional linguistics that can make this division, and general linguistics can also be divided into * * * time linguistics and diachronic linguistics. All kinds of linguistics mentioned above are also called micro-linguistics, because they focus on the language structure itself. Correspondingly, all categories of applied linguistics formed by multidisciplinary integration are macro linguistics. To sum up, theoretical linguistics can be summarized as general linguistics, specialized linguistics and diachronic linguistics. Historical Comparative Linguistics Historical Comparative Linguistics Historical Comparative Linguistics Descriptive Linguistics General Phonetics Historical Comparative Phonetics (Dialectics) Descriptive Phonetics General Lexicology Historical Comparative Lexicology Descriptive Lexicology General Grammar Historical Comparative Grammar Descriptive Grammar General Semantics Historical Comparative Etymology Rhetoric Methodology Dictionary Compilation Other theoretical parts of morphological stylistics (II) Applied linguistics can be divided into broad and narrow sense. Applied linguistics in a broad sense refers to a new language discipline which is produced by the intersection and integration of linguistics and other disciplines. It comprehensively uses the research means and methods of various disciplines to study language, thus establishing a new discipline. Applied linguistics in a narrow sense mainly refers to language teaching, and refers to the application of linguistic theories in language teaching, such as studying language acquisition psychology and comparing the differences between different languages. Our applied linguistics here is generalized, which mainly refers to some marginal disciplines generated by the intersection of linguistics and other disciplines. 1. Sociolinguistics: As the name implies, it is the product of the combination of sociology and linguistics, and it also absorbs and applies the theories of psychology, anthropology, ethnology and social psychology. It is a comprehensive research discipline. To study the relationship between language and society, especially the relationship between language and social groups, because language is always used in a certain language community, sociolinguistics pays special attention to the relationship between language varieties and social factors and studies them together. Sociolinguistics studies the social essence and social differences of languages, such as regional dialects, social dialects, language contact and mixing, language planning and so on. Sociolinguistics first appeared in the United States in the 1960s, and its name first appeared in 1952. As a discipline, it was born around 1964. Sociolinguistics is of great theoretical and practical value, which deserves our in-depth study. 2. Psycholinguistics: a discipline formed by the combination of psychology and linguistics. Language is the product of society. Personally, language and psychology are closely related, which can be said to be a reflection of personal psychology. Observing a person's language is helpful to understand his psychological cognitive activities. Therefore, psycholinguistics focuses on observing the relationship between language and individuals, and studies the psychological reality, the process of language acceptance and occurrence and grammar similar to children's language acquisition. For example, some linguists put forward the question of "core sentence", which is a simple sentence, affirmative sentence, active sentence and declarative sentence. Psycholinguistics has carried out experiments on this, and the results show that it takes less time to transform a declarative sentence into a negative sentence than a negative sentence into a positive passive sentence (passive voice), which shows that the core sentence is in line with psychological reality. 3. neurolinguistics: A new discipline separated from psycholinguistics in recent twenty years, which mainly studies the relationship between language and brain structure. The central problem is how the brain generates language. The human brain weighs about1450g, and the chimpanzee's head weighs about the same as that of human, but the brain is only about 500g. The human cerebral cortex has a language center, while chimpanzees have no language center. The human cerebral cortex is only 4 mm thick, but the distribution of nerve cells is as much as 1 1 10 power. Although the cerebral cortex is very thin, the oxygen consumption accounts for 1/5 of the oxygen inhaled by the whole body. The brain also has a great demand for blood, and 1/5 of arterial blood from the heart is used by the brain. The research of neurolinguists shows that human language activities are mainly related to some parts of the left hemisphere of the brain. The left hemisphere of the brain, which controls language activities, is responsible for rational abstract thinking, while the right hemisphere is responsible for image thinking. Through the anatomy of the brain, it can be seen that the related part of the left hemisphere of the brain that controls language is larger and more complicated than the corresponding part of the right hemisphere, even for infants. Some children under the age of 10 need to remove the left hemisphere cortex because of brain tumor, but it does not affect their language ability, which shows that children's brain psychological process can be transferred from the left hemisphere to the right hemisphere. But for adults, if the left hemisphere of the brain is removed, the language ability will be completely lost. At present, the relationship between language and brain is mainly observed through aphasia. Aphasia is a disease in which the brain mechanism is damaged, resulting in loss of speech ability or speech disorder. Neurolinguists are looking for a connection between aphasia and a certain part of the brain. At present, the research shows that there are three areas related to aphasia in the brain: one is the big bubble card area, which is aphasia caused by injury, and it is very difficult to speak and has poor pronunciation, and generally loses functional words, such as a.in.for in English; Secondly, in Wiernik district, aphasia caused by this part of the injury shows that the patient's language is still fluent and pronunciation is not difficult, but his speech lacks content, repeats and contains many function words, which makes people incomprehensible; Third, the damaged Haier district has caused word deafness. The patient can't understand what others say. He can hear the sound, but he can't understand it, but he can understand it through written language. The research of neurolinguists further shows that the left brain is in charge of language. Damage to the left brain will lose or partially lose the language ability, and damage to the right brain will lose the ability to think in images. Now linguists begin to use "cerebral blood flow" and "EEG" to study the relationship between language and brain. For example, the action of stopping p is very similar to the action of lips when blowing candles, and the muscle action is the same. So, is the behavior in the brain the same? Sapir guessed (there was no research condition at that time) that there was an essential difference between them. Recent EEG experiments confirmed this conjecture. When people blow out candles, there is no difference between the waveforms of the left and right hemispheres of the brain, but when P is emitted, the average voltage of the left hemisphere of the brain increases obviously, while the right hemisphere does not change. Experiments show that the language mechanism in human brain is unique, while other animals have no such mechanism. The mechanism of human language is mainly in the brain, and the internal relationship between brain and human language is still insufficient. The origin of language and the relationship between language and thinking are still difficult to break through. The key point is that our research on the mechanism of human brain is not enough to answer the above questions. If we really study the relationship between language and human brain thoroughly and unlock the secrets between them, we can imagine that the history of language and linguistics will write a brand-new page. 4. In addition, there are mathematical linguistics, statistical linguistics, experimental phonetics and so on. Like statistical linguistics, the statistical study of the author's word frequency can provide strong evidence for exploring the author's language style. For example, in Pushkin's The Captain's Daughter, according to statistics, the pronoun "I" appears every 25 words. The statistical results can also provide a basis for compiling dictionaries. For example, someone counted the words used in English literature, and the results showed that the most commonly used 736 words accounted for 75% of all the words used in the investigated literature. Mastering these words can understand 3/4 of the literature, mastering 1000 common words can understand 80% of literary works and 90% of spoken words. Statistics can also determine the proportion of loanwords in the language. For example, Chinese loanwords account for 75% in Korean, and 55-75% in modern English are borrowed from French, Latin or other Roman languages. The first 20 words commonly used in Chinese are: 1. I have learned that the country is not in the third year of the National People's Congress. For another example, there are tens of thousands of Chinese characters, and how to select commonly used Chinese characters from them requires analysis and statistics of the literature. According to relevant research, the conclusion is that the occurrence rate of 2000 commonly used Chinese characters is 90%, 3700 Chinese characters account for 99.9% of the general literature, and other tens of thousands of Chinese characters only account for 0. 1%. These achievements provide a basis for compiling dictionaries, compiling textbooks and storing Chinese characters in computers. From the achievements of applied linguistics, we can see the important position of linguistics in the discipline system: it has a very close relationship with physiology, psychology, physics, sociology, ethnology, anthropology, culturology, neurology and other disciplines. In the past, linguistics was learning from other disciplines, their viewpoints and methods. Now linguistics has become a discipline that exports methods and opinions, such as literature, sociology, psychology, ethnology, etc., and fully absorbs the research results of linguistics for its own use. Nowadays, computer science, especially fully accepting the theoretical methods of linguistics, making full use of the research results of linguistics, such as establishing a computer thesaurus and automatically processing natural languages by computers, all need the research results of linguistics. The application of linguistic achievements in computer science, on the one hand, makes the computer, as an extension of the human brain, expand its functions and improve its utility, on the other hand, makes the language obtain a new expression form, that is, besides spoken language and written language (written record), it obtains a third form-man-machine dialogue (computer language). Of course, there are still many specific problems to be dealt with in man-machine dialogue, such as the fuzziness of natural language, which is the function of human brain, while computers are relatively mechanical and not as flexible as human brain. We can say that linguistics is not only an ancient science, but also a young science (the establishment of modern linguistics is only a hundred years), a leading science and a pioneer force in the humanities. So Piaget, a Swiss psychologist, commented on linguistics in this way: "Linguistics is the most advanced leading discipline in the humanities, both in terms of its theoretical structure and the accuracy of its tasks, and it also plays an important role in other disciplines."