Market segments are groups of consumers, who share common needs and characteristics. The common segments a business may use are:
Age
Gender
Family Size
Generation
Income
Occupation
Ethnicity
Nationality
Religion
Social class
These are just demographical segments, others like geographical variables such as, region of the world, Country size, Population density and climate. Also behavioural variables are also taken into account, such as brand loyalty and product usage rate. Sometimes a business may factor in psychographical variations, such as life style, personality and attitude.