Is it possible to use CiviCRM if I am a federation that wants to manage his associations with his members? How do I manage organizations and households in such a case? Thanks.
You can create your associations as organisation (or create an organisation sub-type "association") and create relationships between your main organisation (the federation) and the associations.
Another way might be to use civimember, if you have to deal with membership fees, but it depends on how you handle your membership structure, and you should probably read the chapter on civimember in our book and experiment