Drupal 7 has a nice built-in Fields functionality which can be used to add fields to any entity. As applied to users, this replaces the previous Profile module which was used in Drupal 6 to add fields to users. However, right after creating a new Drupal 7 site, I couldn’t figure out how to add fields to users.
I followed these instructions
Just go to:
Configuration > People > Account Settings
Then click on the Manage Fields tab, and then just manage the fields just like you would for a Content Type.
But there wasn’t a “Manage Fields” tab on that page. Going to the URL directly,
admin/config/people/accounts/fields, was redirecting me back to the Account Settings page. After banging my head against the wall for ten minutes I finally realized that the reason I couldn’t see this tab was because the “Field UI” module wasn’t enabled. Go to the List Modules page, enable that module (and its dependencies), and now you should be able to add fields to users.