1. Classification of a mass of data (obtained from research or survey) into categories and sub-categories on the basis of one or more chosen criteria. 
2. Hierarchical arrangement of a society into different layers (strata) on the basis of a distinguishingcharacteristic such as age, gender, life style, race, status. 
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USAGE EXAMPLE

Stratification in society often occurs between classes of people based on income with lower and higher classes being divided geographically.