What do these things have in common, you're asking? They're just a few examples of the many hundreds of things that your parents controlled for you when you were a child. As a kid, you didn't have a say in very much that went on; your parents made decisions about everything from the cereal you ate in the morning to the pajamas you wore at night. And it's a good thing, too - kids need this kind of protection and assistance, because they aren't mature enough to take care of themselves and make careful decisions on their own.
But eventually, kids grow up and become teens. And part of being a teen is developing your own identity - one that is separate from the identities of your parents. It's totally normal for teens to create their own opinions, thoughts, and values about life; it's what prepares them for adulthood.
But as you change and grow into this new person who makes his or her own decisions, your parents may have a difficult time adjusting. They aren't used to the new you yet - they only know you as the kid who had everything decided for you and didn't mind.
In most families, it's this adjustment that can cause a lot of fighting between teens and parents. You want to cover your walls with posters; they don't understand why you don't like your Sesame Street wallpaper anymore. You think it's OK to hang at the mall every day after school; they would rather that you play a sport. Clashes like these are very common between teens and parents - teens get angry because they feel parents don't respect them and aren't giving them space to do what they like, and parents get angry because they aren't used to not being in control.
It's easy for feelings to get very hurt when there are conflicts like these. And more complicated issues - like the types of friends you have or your attitudes about sex and partying - can cause even bigger arguments, because your parents will always be intent on protecting you and keeping you safe, no matter how old you are.
The good news about fighting with your parents is that in many families the arguing will lessen as parents get more comfortable with the idea that their teen has a right to certain opinions and an identity that may be different from theirs. It can take several years for parents and teens to adjust to their new roles, though. In the