Social stratification is a system by which society ranks people in a hierarchy. It is a characteristic of all societies and involves both social inequality and beliefs that justify this inequality. Social stratification results in some groups systematically experiencing advantages while others are disadvantaged based on characteristics like race, class, and gender. It can take the form of caste systems, like in parts of India, where one's social position is fixed at birth, or class systems where social standing depends more on individual achievement and some social mobility is possible.