It is defined by being any kind of hostile or destructive behaviour of an individual. It can be pointed not only to other people, objects or animals, but also to his/her own as autoagressivity. It can be both verbal and physical, applied directly or indirectly towards the victim, manifested passively. For example : stubborness, procrastination, silent opposition, the style " says like him, do as I do it", are forms of passive agressivity.

Not all agressive behaviours make antisocial acts, as not all antisocial acts are accompanied by agressivity. For example, the activity of sportspeople during events is not an antisocial act. Pickpocketing is an antisocial act but is not accompanied by violence or agressivity.

Agressivity can take multiple forms which can be expressed phisically, communicated verbally or even nonverbally: anti-predator agressivity, fear induced agressivity, predator agressiviy, domination agressivity, inter-masculine agressivity, isolation induced agressivity, irritable agressivity, maternal agressivity, species specific agressivity, territorial agressivity, sex related agressivity and agressivity induced by brain stimulation (the hipotalamus). There are two subtypes of human agressivity:

• The instrumentally-controled subtype (with a purpose oriented to a purpose);
• The impulsive-reactive subtype (who often provokes incontrolable, inadequante or unwanted actions).

It is one of the main sources of human agressivity. Frustration (the loss) of the object and the social relationships frustration lead to hostile and destructive manifestations from the one suffering. Moreover, children usally have a lower frustration tolerance than adults do.

Fear, anxiety is another important source of agressivity. Both children and adults who are not able to express their fears through words often behave agressively whenever they feel anguished or threatened. The agressivity of a child is sometimes manifested towards the object that produces the fear : the child throws stones to the dogs he is afraid of, he hits the parent who threatened him with the retreat of love ( "You are a baad kid, I don't love you anymore") or with leaving him alone ( "I'll go to another child"). To a child who has an unsecure attachment towards parents is hard to console when separated, while in the moment of reunion, instead of cheering, the child manifests agressivity towards the family : arguing, hitting, bitting, crying, screaming. Adults can also behave as such when feeling anxious or threatened.

The familial environment and socially agressive, violent and antisocial take a big part in the development of a violent and agressive conduct, but also of an antisocial one, speaking of children and teenagers. Families marked by domestic violence, poor social environments, underprivileged, where violence and deliquency become normal, completely distorsion the perception of these aptitudes and conducts, children putting value on them as they saw adults doing or behaving aas such withot having any other behaviour alternative. In other words, they do what they saw in their family and the environment they grew up in.

Other factors that lead to agressivity were identified : heat, urban aglomeration, phisical pain or disease. Therefore, in such conditions which are beyond our control it is important to remember that us, but also the ones surrounding and esecially children have a lower tolerrance than usual to frustration and that is why we could all manifest more agressively than usual.

Agressivity is born says Sigmund Freud and Konrad Lorenz. People are born with predispositions or impulses to be violent and agressive. With this not being able to be removed, it is needed to find through education, indestructive ways of chanelling negative energy.Some factors that influence agressivity do exist:

• Neuronal influences-some areas of the cortex facilitate an agressive behaviour after electrical stimulation
• Hormonal influences-males are more agressive than females due to hormonal differences
• Bio-chemical influences-an increase of alcohool in blood, or low glicemy can intensify agressivity

Verbally provoking, but also phisically often makes a good source for an agressive behaviour for both children and adults.

Videos with violent and pornographic character, violent computer games, lead to an increased frequeny of agressive, violent and antisocial behaviours, with children accessing such materials from young ages. A desensibilisation of children to the suffering of other people or animals takes place. More than a catharsis , as it is oftenly affirmed, this can easily lead from sadistic acts commited by very young children, to physical, verbal and even sexual abuses commited by children and teenagers. Facts and statistics bear witness in this sense.