Peers are people who are part of the same social group, so the term "peer pressure" refers to the influence that peers can have on each other. Although peer pressure does not necessarily have to be negative, the term "pressure" implies that the process influences people to do things that may be resistant to, or might not otherwise choose to do. So usually the term peer pressure refers to socially undesirable behaviors, such as experimentation with alcohol and drug use, rather than socially desirable behaviors, such as academic success, although it could be applied to either, and either could be a positive or a negative experience for the individual.
Peer pressure is usually applied to younger people, especially teenagers. Adolescents are particularly vulnerable to peer pressure, because they are at a stage of development when they are separating more from their parents' influence, but have not yet established their own values or understanding about human relationships or the consequences of their behavior. They are also typically striving for social acceptance at this stage, and may be willing to engage in behaviors that will allow them to be accepted that are against their better judgment.
Parents often worry about peer pressure, particularly in relation to potentially addictive activities, such as alcohol and drug use and sexual behavior, and to a lesser extent, food and eating patterns, video game playing, gambling, shopping and spending, and illegal activities. Parents are rarely concerned about peer pressure to engage in sports and exercise, as these are typically seen as healthy social behaviors. This is appropriate, as long as the exercise or sport does not become an unhealthy way of coping, excessive to the point of negatively affecting their health, or dangerous (as in dangerous sports).
Although parents worry about the influence of peers, overall, parents have a greater influence on whether children go on to develop addictive behaviors than peers do. Addiction is a complex process, which is affected by many different factors, so peer pressure alone is unlikely to cause an addiction.
However, peer pressure may increase the risk of other harms, which can be even more dangerous than addiction, such as driving under the influence of alcohol or other drugs, overdose, poisoning, asphyxiation, STDs and accidents.