Create node from another node How do I create a node from an existing content type on front end? Let's say we have a article i need to associate tags with it in a fashion.
For example a book of tags which a user can view . Either we can create a book or we can add tags to an already existing book. Those books are binded to a user also.
Well if what I getting from you is right then you have to look into Taxonomy Vocabulary and terms.

So you can have a Vocabulary of Sports but under sports there are so many taxonomy terms - types of sports, like footbal,hockey,basketball etc 

then for your content type you add a taxonomy field mapped to the sports vocabulary

now users can create content and add the various tags/terms to it.

if not then you may have to look at using books in drupal