Sociolinguistics defines the phenomenon as word borrowings (loanwords), a formal outcome of language contact. But language contact is not all. In the field, there are also language functions, language varieties, language attitudes, language changes, and language plans. All are interesting to study and presented in this book. Also in this book readers can find ; key concepts in the study (speech-community, acrolect, diglossia, code-crossing, interference, jargons, slang, etc), a brief introduction to some most important sociolinguists (William Labov, Dell H Hymes, joshua A Fishman, etc.), statistics on languages (English, Indonesian, Chinese, pidgins, and some other languages), as well as, selected qoutations related to the topics taken from various authors on books on sociolinguistcs.