Plain

A plain is a broad expanse of flat or gently rolling land with relatively little relief. Plains form through processes such as sediment deposition in river floodplains, the leveling effects of glaciation, or the accumulation of wind-blown loess that creates extensive, level surfaces. Soils on plains are often fertile, especially where alluvial material builds up, supporting grasslands, crops, and human settlement. Compared with plateaus and mountains, plains show minimal elevation change over large areas, though regional variations exist.

Geographic examples are widespread. Notable plains include the Great Plains of North America, the Indo-Gangetic Plain of South Asia, the North European Plain, the Pannonian Plain in Central Europe, the Pampas of Argentina and Uruguay, and the Llanos of Venezuela and Colombia. Plains span a wide range of climates, from temperate agricultural belts to tropical grasslands and floodplains. Their ecology varies from tallgrass prairies to tropical savannas, often shaped by rainfall and soil type. They are commonly used for farming and grazing; floodplains can yield rich soils but may be subject to seasonal flooding.

In language, plain also describes something simple, unadorned, or easily understood. Plain language or plain English refers to writing and speech designed to be clear and accessible to a broad audience, avoiding jargon and complex syntax in public communications and information materials.

Etymology traces plain to Old French plains or planus from Latin planus, meaning flat or level. The term encompasses both physical landscapes and metaphorical uses, with distinct senses in geography, linguistics, and everyday description.