Before people didn't always get to watch musicians play there music or even listen to it, they would usually watch it in bars, the theatres, on the radio, the juke box or the video juke box that was until the television was invented. When televsion was invented music wasn't that important until top of the pops was made in the 1970's. Then in the 1980's cable was invented with MTV as a 24 hour music channel which made a need for music videos, then in the late 80's and 90's growth of the genre based channels evolved also black music breaks in to the industry things such as hip-hop, reggae, and R&B started to come out. And now a days you can watch music videos in your house, on the net, and even on you pone.
The age group that would follow pop is the young teens and younger children getting in to their teen years. Pop is appropriate for young girls and children because it doesn't influence them in any wrong way, it just allows children and teens to act there age. Their audience may take the fashion senescence of their role model in the pop industry and may want to be a singer but will be happier to just listen to their music.
This genre relates to the 'Blumers and Katz theory 1974' on what the consumers choose and use...... The genre usually uses Diversion, meaning that it allows escape from everyday life, problem, and routines and you'll also find that personal relationships is used, using the media for emotional and other interaction e.g substituting soap operas for family life.
Stuart Hall is a theorist. His one of the main theorist of the reception theory. Stuart Hall had established what ever it be from a programme to a film or a book, the person who created it will see it in one way and the people will always interpreter what ever it is they see in their own way based on cultural background and life experiences.