Peers are those who form part of the same social group. Peer pressure implies an influence to do something that you may not otherwise want to do.
Parents often worry about peer pressure, particularly in relation to potential addictive activities, such as alcohol and drug use and sexual behaviour etc.
Peer pressure alone is unlikely to cause an addiction.
Adolescents are particularly vulnerable to peer pressure. This is because they are pushing boundaries and asserting themselves as young adults.