Aggression is a physical or verbal behavior intended to cause harm. There are two types of aggression, hostile aggression and instrumental aggression. Hostile aggression is aggression that is driven by anger and is performed as an end to itself. Instrumental aggression is aggression as an instrument to accomplish other needs. There are three theories of aggression. First is aggression as a biological phenomenon (Archer, 1988). Biological phenomenon sees aggression as an instinctive behavior, an innate, unlearned behavior pattern exhibited by all member of a species. Aggression also has an adaptive function in which to gain resources, defending against attack and eliminating male rivals (Baron and Richardson, 1994).

Second is a response to frustration. Frustration is often raised by relative deprivation, which is the perception that one is less well off than others with whom one compares oneself. If a there is a frustration and anger plus aggression cues, it would lead to aggression. Third, is a learned social behavior, aggression emerged because of observational learning, as Bandura (1997) purpose is that we learn by watching or observing and imitating. The source of this imitation is family and culture. Aggression has a reward such as authority, power and exploitation by media.

Aggression is influenced by: aversive incidents, arousal, aggression cues, media influences and group influences. Aversive incidents are pain, heat and attack. Arousal feeds one emotion or another depending on how a person interprets them. Aggression cues like guns, it gives psychological distance between aggressor and victim rather than a knife. This cue is what makes someone aggresive.

Media plays a huge part in defining aggression. Violence follows television and video games. A person that often watches violence on television and play video games tends to feel numb towards criminality. Television and video games might give desensitization to the subjects that will extinguish emotional response. Television and video games might also give person a social script which provided mental instruction for how to act in various situations. Television and video games also provides altered perceptions, which mold our conception of a real world. Cognitive priming also a part of the effect of the television and video games, in which watching violent videos primes aggressive-related ideas. People who play video games tend to be more aggressive than a person that only watches the television, because they are indirectly do violence. Group influences also influences aggression. Groups can intensify aggressive reaction because of diffusing responsibility, social contagion and social identity.

As we can see that groups could intensify aggressive reaction. Therefore, we often see the way teenagers act, they get together in groups and they could end up do aggressive things. Research supports the statement that teenagers often erupt with aggressiveness. They are in the brink of youth, they feel alive and they are searching for further stimuli to explore their capabilities.  All the theories stated above proves the points that teenager aggressiveness are supported by their environment, the media, their peers and none other than the biological factor itself. It is important to parents to detect early signs of aggression in teenagers.

There are positive and negative forms of aggression. Positive forms of aggression, for example is when teenagers channel their aggression into video games, instead of disputing their aggression towards their peers or siblings. This positive form of aggression is a way for teenager to channel their aggression urges, not necessarily because of this, teenagers should bury themselves in aggression, no. Negative one is when they take it out on someone, maybe their peers, siblings or even parents. Parents must always be alerted towards the changes in their teenage child, because teenage years is the prime years where they could be molded into becoming a better person, or they would lose track and ends up a wreck.

Parents here act as supervisors and not a cage. The parents should act as if they are letting go of their children to explore the world, meanwhile they still get ahold of their teenagers reins. Therefore, the teenager will respect the parents as they should be. They will appreciate the space their parents giving them, and also acknowledge the responsibility the parents yield to their shoulders.