INTRODUCTION TO LINGUISTICS
Linguistics The study of language. As a scientific discipline built on objective principles, linguistics did not develop until the beginning of the 19th century. The approach then was historical as linguists were mainly concerned with the reconstruction of the Indo-European language. With the advent of structuralism at the beginning of the 20th century, it became oriented towards viewing language at one point in time. The middle of this century saw a radically new approach-known as generative grammar-which stressed our unconscious knowledge of language and underlying structures to be found in all languages.
Kind of pure linguistics such as : 

• Phonetics is the study of human sounds.
• Phonology is the study of the sound system of a language or languages.
• Morphology is the study of the words as they express grammatical categories.
• Lexicology is the study of the structure of the lexicon. 
• Syntax is the study of sentence structure.
• Semantics is the study of meaning in language

Kind of apply linguistics such as :

• Sociolinguistics is the study of how language is used in society.
• Psycholinguistics is the study of language is relation to our cognition and in particular to the way we acquire our first language.
• Applied linguistics studies the uses to which linguistic insights can be put, especially in second language teaching.
• Language change is the investigation of the manner in which languages change their structure over time.
• Language typology is the study of the synchronic structure of languages for the purpose of classifying them according to recurring patterns and regularities.