# Privacy and Security Issues in Online Social Networks
## 3 Privacy and Security Threats in OSNs  
User-generated content on social media may include users' experiences, opinions, and knowledge. In addition, it may also include private data, for example, name, gender, location, and private photos [7]. Online-shared information is electronically stored and is therefore permanent, replicable, and reshareable [8]. OSN users generally face the challenges of managing their social identity while compromising their social privacy. The popularity of social media is such that worldwide active users of social media are expected to reach around 2.95 billion by 2020, which is about one third of the world's entire population ([[https://www.statista.com/topics/1164/social-networks/](https://www.statista.com/topics/1164/social-networks/)]([https://www.statista.com/topics/1164/social-networks/](https://www.statista.com/topics/1164/social-networks/))). The total active users on different popular social media networks are presented in Table 1 ([[https://www.statista.com/statistics/272014/global-social-networks-ranked-by-number-of-users/](https://www.statista.com/statistics/272014/global-social-networks-ranked-by-number-of-users/)]([https://www.statista.com/statistics/272014/global-social-networks-ranked-by-number-of-users/](https://www.statista.com/statistics/272014/global-social-networks-ranked-by-number-of-users/))).  
Taking into account this global number of users, privacy is one of the obvious and critical issues regarding OSNs. Various privacy issues are fostered because of OSNs, such as surveillance, in which the social sphere of OSNs changes to a commercial sphere and OSN service providers supervise user actions for market force access control. Standard OSNs share users' personal data with third parties for advertisement purposes that may be exploited [9]. Likewise, OSN users leave digital imprints when they browse OSN sites, and therefore are targeted as data sources for commercial uses and user profiling.  
Social-networking tools have changed the way we interact in our personal and professional lives. Although they play a significant role in our social and business lives, at the same time they bring about high risks concerning privacy and security. As hundreds of thousands of users use OSNs on a regular basis, they have attracted the attention of attackers more than any other target in recent years. Because of the high usage of social media, online users have been exposed to privacy and security threats. These threats can be categorized into classic and modern threats. Classic threats are online threats that not only make OSN users vulnerable, but also other online users who do not use any OSN. The second type of threats is modern threats, which are related to OSN users only  
\begin{table}
\begin{tabular}{c c} \hline \hline
**OSN** & **Total Active Users in Millions** \\ \hline Facebook & 2047 \\ YouTube & 1500 \\ WhatsApp & 1200 \\ WeChat & 938 \\ Instagram & 700 \\ Twitter & 328 \\ Skype & 300 \\ Viber & 260 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Popular Online Social Networks (OSNs) and their total active users in millions.  
because of the OSN infrastructure that can compromise user privacy and security [10]. A 2016-based finding, NopSec, the State Vulnerability Risk Management Report ([[http://info.nopsec.com](http://info.nopsec.com)]([http://info.nopsec.com](http://info.nopsec.com))), claims that organizations are using inadequate risk-evaluation scoring systems. The report states that social media are not included in the risk-evaluation scoring system but they are one of the top types of platform for cybersecurity.