It is actually segmenting (simple meaning is separating ) the population based on age,sex,income,life style ,occupation etc.
What Are Demographic Factors In Segmentation Of Marketing?
A method of separating the market place into buying segments you would not want to target lawn tractors in the middle of new york city or highrises in tightwad missouri so it is a scale to locate and target markets for sales
The most important demographic factors that affect market segmentation are age, gender, marital status, educational qualification, income level, wealth, geographic location, size of family etc.