How to add extra fields to user profile in Drupal?

Step 1. - Create custom module -For Example My custom module name is extra_user_profile
Folder Name - extra_user_profile

Files - extra_user_profile.nfo, extra_user_profile.module, extra_user_profile.install

Step 2.

extra_user_profile.nfo file:-

name = Extra User Profile

description = Add new field in user profile

core = 7.x

version = "7.x-2.5"

core = "7.x"

Step 3.

extra_user_profile.module file:-

<?php

Step 4.

extra_user_profile.install file:-

<?php

/**

 * Implementation of hook_enable().

 */

function extra_user_profile_enable() {

  // Check if our field is not already created.

  if (!field_info_field('field_nickname')) {

    $field = array(

        'field_name' => 'field_nickname', 

        'type' => 'text', 

    );

    field_create_field($field);

    // Create the instance on the bundle.

    $instance = array(

        'field_name' => 'field_nickname', 

        'entity_type' => 'user', 

        'label' => 'Nick Name', 

        'bundle' => 'user',

        'required' => TRUE,

        'settings' => array(

            'user_register_form' => 1,

        ),

        'widget' => array(

            'type' => 'textfield',

            'weight' => '1',

        ), 

    );

    field_create_instance($instance);

  }

}

Step 5 Enable Module

Now Nickname field is available in User profile page
Enjoy....!!!!