This document discusses the different varieties of English based on region, social factors, medium, field of discourse, and attitude. It identifies five main types of linguistic variation: regional dialects, social variation based on education, socioeconomic group, age, and ethnic/gender, field of discourse variation based on the topic being discussed, medium variation based on whether it's written or spoken language, and attitude variation based on social prejudices. It also outlines some of the major standardized national varieties of English including British, American, and others.