What is a minority group?

Wikipedia define a minority as a "sociological group that does not constitute a politically dominant voting majority of the total population of a given society." There are a lot of minority groups, for example "economic minorities", "age minorities" or sexual minorities.

Economic minorities
The term: economic minorities describes a social group which has a lot of working poor or unemployed people.

Age minorities
The age minority contain a group of people with the same age. That could be old people or young people like children.

Sexual minorities
To this group counts lesbian, gay, bisexual and transgender.