A method of forming unique, private, personal, virtual social networks on a social network system that includes a database storing data relating to corresponding user entities. The method includes: a first user entity sending an invitation to a second user entity, recording in the database the second user entity as a direct contact of the first user entity and determining that third user entities, directly connected to the second user entity, are indirect contacts. A unique, personal, social network formed from direct and indirect contacts is thereby created for each user entity. Each user entity is able to control privacy of its data with respect to other user entities depending on the connection factor to that other entity and/or that other entity's attributes.