May i use drupal for a social network?

Group & Profile are extra modules for Drupal that can be added to a social network where multiple communities, departments, or teams are organized together on an intranet or portal.

Yes, there a lot of articles in the web that includes the needed modules for a custom Social Net using Drupal.
  article one
  article two
 and many more, just Google "module of social networking site in drupal"