Online social networks (OSNs) is one of the most popular medium for communicating, sharing, and publishing a considerable amount of information. OSN popularity often faces the challenge of dealing with unwanted messages and hidden malicious purposes in it. Based on recent studies, social network users can easily expose their confidential details with others. Misuse of this information can cause damage in virtual and real world. In this paper, main categories attacks are given on social network online security and privacy in four categories classic, modern, hybrid and children special attacks and ways that can be used to protect against different types of attacks used OSN users is the social network operators, security companies, and researchers are provided. Finally, eight ways to prevent these threats is presented.