params instead contains a hash of hashes, a construction we first saw in Section 4.3.3, which introduced the strategically named params variable in a console session. The debug information above shows that submitting the form results in a user hash with attributes corresponding to the submitted values, where the keys come from the name attributes of the input tags seen in Listing 7.17; for example, the value of

with name "user[email]" is precisely the email attribute of the user hash.

                   Although the hash keys appear as strings in the debug output, internally Rails uses symbols, so that params[:user] is the hash of user attributes—in fact, exactly the attributes needed as an argument to User.new, as first seen in Section 4.4.5 and  appearing in Listing 7.21. This means that the line

         is equivalent to