To many people the major purpose of television could not be depending on a single program. In my opinion, TV is a tool for education and entertainment as well.
Natural science programs, documentaries, and educational programs--these kinds of the TV programs are to educate. For example: When we have a biology course, our teacher always shows some TV programs to compliment our text book. Most of these programs also show additional information that is not covered in the text book, so we can gain more knowledge from the programs than from text books alone. Consequently, they have expanded my horizon.
I saw a TV show recently called The Quiz Show. This was a Chinese history competition and everyone had a chance to join in. I learned a lot about Chinese history and I also answered some questions correctly and immediately. I benefited a lot from this show and I thought it was a good idea for teachers using this program to educate.
In term of entertainment, most cartoons, soap operas, or violent crime television shows are to entertain and simulate. We watch these shows when we are bored or tired. For example, the Super Girls Competition, a recent singing program, is popular among Chinese. People want to get more fun from this show or even want to pretend like a judging person to guess which girl is the best. These kinds of the programs help people relax.
In short, TV is both educational and entertaining. If we can use this media properly and if we can watch TV appropriate numbers of TV programs as well as a win-win situation for all.