The document discusses the classification and development of English vocabulary. It covers: - Common words, literary words, colloquial words, slang words, and technical words can be classified by level of usage. - The historical development of English vocabulary from Old English, Middle English to Modern English, with influences from Latin, French, and other languages. - After WWII, rapid growth in vocabulary was driven by advances in science/technology, socio-economic changes, and influence from other cultures and languages. New words emerged in many domains like space, computers, social movements, education and more.