Associate an user to a taxonomy term I'd like to associate an user to a taxonomy term. I create users in a process import managed by rules. 

I didn't found a solution with an existing module so I try to develop mine. I've also installed Entity reference module but I feel confused. 

I've added a field_user in my taxonomy term fields management.I've added a field_conventions in my user field management.

I do not understand how to associate one or many terms to an user with rules. 

I found User Terms module but unfortunately only for a Drupal 6.x
User profiles are fieldable in Drupal 7, you can add a taxonomy field already, with nothing but core. You don't need Entity Reference or any other modules, you can simply  add field_taxonomy to your user. Sure, it is a bit opposite to "add users to terms" you described, but later, if you need it for Views etc, it doesn't matter which way it was created - there is a connection between user and term, and you can use it.