The few main definitions of loneliness state that loneliness is an unpleasant, emotionally disturbing experience which stems from dissatisfaction with the quality or quantity of established relations. The period of adolescence, a period in which an emotional and bihevioral independence from ones parents is established, as well as the time when some stonger bonds with peers are formed, is stated as the period of change and developmental tasks which is assumed to be the most suitable time for the occurence of loneliness. There are many classifications of loneliness, but the most famous one is considered to be Weisses. His classification of loneliness divides it into social (which occurs when a person is excluded from a social network) and emotional (caused by the lack of intimacy in interpersonal relationships). Loneliness can manifest in many ways, and in the most recent of times the most famous ones to be considered are affective manifestations which can lead to a state of anxiety, unrest and tension. In many situations it is very difficult to recognize the difference between the behaviours which directly led to the state of loneliness and behaviours which are the result of loneliness in adolescence. One of the potential problems in adolescence is stress which is conected to socializing with peers. Peers establish social relations, which then form a social network. Social network is important because it shows the quality and quantity of the relations of lonely and potentially lonely persons with others whom they are close to. This view puts into perspective the importance of reciprocity of closeness. In conclusion, loneliness can include some pshychic, bihevioural and cognitive problems which can be resolved with different types of therapy.