No widespread language is uniform from place to place. A dialect is a regional or social variety of a language marked by patterns of pronunciation, vocabulary, and grammar.

Dialects of the same language are typically mutually intelligible, though intelligibility is a gradient. Standard varieties are themselves dialects that gained prestige through history and institutions. Isoglosses on maps show where particular features change across space.

Social dialects reflect class, ethnicity, or peer group. Dialect research documents variation without ranking varieties as pure or corrupt. Education that respects dialect diversity while teaching a standard supports both identity and wider communication.

• Regional or social variety of a language
• Marked by sound, vocabulary, and grammar
• Usually mutually intelligible with related dialects
• Includes prestige standards as one dialect among others