My daughter loves TV and loves the commercials. Is there a way to explain advertising to her?
The best approach is to show rather than tell. Try watching your daughter's favorite TV show with her and pay special attention to the commercials. Explain the difference between the program and the commercial. Later, ask her if she remembers the many products there are in a grocery store. Explain that because there are so many choices, the people who make a particular soda or cereal want to convince you through the commercial to buy their product instead of somebody else's.
Have your daughter pick a new product to taste-test, like a soda or a cereal. Then go to the supermarket and let her find that product. If it's a kid cereal she will probably find it within her reach. Explain that manufacturers ask to have the cereal down low so that kids can see it.
Buy her choice, and also buy a similar brand. Then go home and conduct a taste-test with other family members. Make an event of it. Blindfold them, and let them pick their favorite. During the process, remind her of the points that the advertiser was stressing in the commercial: Was the cereal really crispier? Did it truly have more raisins?
If the product your daughter picked from the TV commercial was the choice of the family, then she wins. Either way, she's going to learn how much or how little she can trust commercials and how important her own judgment is. She'll take pride in making the decision, and the commercials may have less power over her in the future.