Target Audiences, important?

So I would love to know how a target audience is decided for a particular product or service.
Advertising for a product involves marketing, but in order to market you must first decide on an audience.
Deciding on a target audience is one of the most important marketing factors, if the wrong target audience is decided then the product or service will not sell well.

You must first narrow your target audience down, for example to an age range or a gender.

If someone is trying to create a new children's television show for example they may take into consideration a specific child age range so it could be targeting 10-16 years or age or 2-9 years of age. This will then depict what television programmes they show, or what time they air until.

 In the night garden is aimed at a younger age group and therefore is shown early in the morning on CBeebies, which is a channel broadcast specifically at children up to the age of about seven.

Icarly is shown on Nickelodeon, a channel aimed at children up to the age of about sixteen. It uses real people and the people in the show are around the same age as the traget audience which makes then automatically more relate-able to the audience and therefore this makes easy viewing, it is a comical show that sometimes targets real life situations although they try to go about it in a slightly less serious way it does try to prepare young teens for situations they may have to encounter at some point in their life.

A target audience is very important to anything a business decides to do and is a main factor that decides how much profit or loss a company will make.