Stratification is the building up of layers. Stratified is an adjective referring to the arranging of layers, and is also the past form of the verb stratify, to separate or become separated into layers. They may refer to:
- In mathematics, statistics and applied science
- Stratified sampling, in statistics
- Stratified fuel charge, or ultra lean burn, the use of lean mixtures in an internal combustion engine with unequalized pressure in the cylinder
- Fuel charge stratification, an internal combustion process using gasoline direct injection to reduce fuel consumption and emissions
- Fuel stratified injection (FSI), the operation of a stratified fuel charge in an engine using direct injection
- Fuel charge stratification, an internal combustion process using gasoline direct injection to reduce fuel consumption and emissions
- In the earth sciences
- Stratification, the layering (strata) of rocks
- Stratification (archeology), the formation of layers (strata) in which objects are found
- Stratigraphy, the study of geological (or archaeological) stratification and strata
- Atmospheric stratification, the dividing of the Earth's atmosphere into strata
- Stratification (water), the formation of water layers based on salinity and temperature
- Lake stratification, the dividing of lake water
- Geographic stratification, the dividing of geographic areas
- In the social sciences
- Social stratification, the dividing of a society into levels based on power or socioeconomic status
- In biology and medicine
- Stratification (botany), where seeds are pretreated to simulate winter conditions so that germination may occur
- Stratified epithelial linings, several types of epithelium characterized by multiple layers
- Stratified medicine, where patients are grouped according to shared biological traits and diagnostic results
- Population stratification, the stratification of a genetic population based on allele frequencies