Demographics are the make-up of a population by age, income and so on. Changing demographics, the demographics of the audience, study the demographics.
In advertising it means the group a product is aimed at, so a broadcaster talks about reaching a younger demographic. The plural is normal, and the singular demographic is now used for one such group.
1noundemographicsThe make-up of a population by age, income and so on.
“The town's demographics have changed, with more young families moving in.”
demographics is a make-up.