It is simply an online community where students and staff can interact, keep in touch with their friends, share photos, arrange event and meetings, post team sheets, blog, etc.
CUSU social network is only for City students and staff, so you can only sign up with your @city.ac.uk email. When you sign up you will be prompted to create an online profile for yourself and upload your picture.
Once you are created you can link yourselves with friends, create groups, or request to join existing groups, including all the Clubs and Societies. Both users must confirm that they are friends before they are linked and group owners must except new members to their groups.
To sign up go to the Social Network