This document discusses language variation and related concepts. It defines the standard language as an idealized variety not associated with any specific region. Accents and dialects are distinguished, with accent referring mainly to pronunciation and dialect encompassing grammar, vocabulary, and pronunciation differences. Dialectology examines regional dialects and identifies boundaries. Bilingualism and diglossia involve two distinct languages in a region. Language planning by governments determines official varieties for public contexts. Pidgins emerge for communication between groups without a shared language, and may become a creole if adopted as a community's primary language.