This document discusses the stylistic classification and historical development of English vocabulary. It covers:
1. The classification of words by level of usage including common, literary, colloquial, slang, and technical words.
2. The historical development of English vocabulary over three periods - Old English, Middle English, and Modern English - and the influences of Latin, French, and other languages at different stages.
3. The rapid growth of the English vocabulary after World War II due to advances in science, technology, and socio-economic changes.