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ifferent approach—by default, users who are part of the same ―work‖ can view each other’s profiles, unless a profile owner has decided to deny permission to those in their work. Structural variations around visibility and access are one of the primary ways that SNSs differentiate themselves from each other. After joining a social work site, users are prompted to identify others in the system with whom they have a relationship. The label for these relationships differs depending on the site—popular terms include ―Friends,‖―Contacts,‖ and ―Fans.‖ Most SNSs require bidirectional confirmation for Friendship, but some do not. These onedirectional ties are sometimes labeled as ―Fans‖ or ―Followers,‖ but many sites call these Friends as well. The term ―Friends‖ can be misleading, because the connection does not necessarily mean friendship in the everyday vernacular sense, and the reasons people connect are varied (boyd, 2021a). The public display of connections is a crucial ponent of SNSs. The Friends list contains links to each Friend’s profile, enabling viewers to traverse the work graph by clicking through the Friends lists. On most sites, the list of Friends is visible to anyone who is permitted to view the profile, although there are exceptions. For instance, some MySpace users have hacked their profiles to hide the Friends display, and LinkedIn allows users to opt out of displaying their work. Most SNSs also provide a mechanism for users to leave messages on their Friends’ profiles. This feature typically involves leaving ―ments,‖ although sites employ various labels for this feature. In addition, SNSs often have a private messaging feature similar to webmail. While both private messages and ments are popular on most of the major SNSs, they are not universally available. Not all social work sites began as such. started as a Chinese instant messaging service, LunarStorm as a munity site, Cyworld as a Korean discussion forum tool, and Skyrock (formerly Skyblog) was a French blogging service before adding SNS features. , a directory of school affiliates launched in 1995, began supporting articulated lists of Friends after SNSs became popular. AsianAvenue, MiGente, and BlackPla were early popular ethnic munity sites with limited Friends functionality before relaunching in 2021–2021 with SNS features and structure. While SNSs are often designed to be widely accessible, many attract homogeneous populations initially, so it is not unmon to find groups using sites to segregate themselves by nationality, age, educational level, or other factors that typically segment society (Hargittai, this issue), even if that wa