Typical teen behavior is influenced by all the physical, emotional and cognitive changes your teenager is experiencing. Teens can often exhibit more extreme emotions and mood swings than children or adults. At times, the confusion of puberty and adolescence can lead teens to a feeling of depression as they worry about their own growth, how others see them, and where they do (or do not) fit in. Girls are more susceptible to these depressive feelings as they tend to focus on negative events more than do boys, who can often distract themselves with sports or other activities. All teens can show great concern and worry about how they compare to their peers. They'll also spend a lot of time sorting out their identity and trying on new personas. This obsession with their personalities and identities leads to a fair amount of egocentrism.
Teens will also start seeing adults and authority figures as fallible, which can often lead to more backtalk, rejection of authority, and general unruliness. However, in their search for their identity, they'll also likely start looking for new adult role models. These behaviors are all part of teens' interest in gaining independence from their parents.
Teens explore their worlds more intently and they are better able to learn new things. As a result, they will also engage in riskier behaviors. Unfortunately, their brains aren't yet well-equipped to always see the consequences of their actions, so parents have to find that fine balance between letting their teens investigate new activities and keeping them safe.
As teens' bodies changes, they're likely to experience some physical awkwardness as they try to navigate in them. This awkwardness usually increases teens' self-consciousness, which can be the source of some of their moodiness. They are also more interested in sex and sexual matters, and will (hopefully) start asking you questions about these topics.