This document discusses language change and how it spreads. It provides three main points:
1) Language changes over time in pronunciation, meaning, and vocabulary. Changes occur due to speaker innovation and are influenced by factors like time, location, and social context.
2) Language changes spread from group to group, style to style, and word to word. Changes originate from both above, which people are aware of, and below, which people are unaware of.
3) Reasons for language change include social status, gender, and interaction between groups. People of higher social status and women often introduce changes, while isolation slows changes. Studying language change involves real-time and apparent-time analysis of usage