In Facebook the friends represent nodes and the relationship between two friends represents links but we can get a lot more information from it, such as gender, age, post list, likes, political affiliation, religion, and so on. And Facebook provides us with a complete Application Programming Interface (API) to work with its data. You may visit the following link for more information:
Another interesting option is the Stanford Large Network Dataset Collection, where we can find social networks' datasets well formatted and anonymized for educational proposes. Visit the following link for more information:
Using the anonymized data, it is possible to determine whether two users have the same affiliations, but not what their individual affiliations represent.