Drupal7 system_settings_form()

This hook adds a button and setting forms, which allow you to configure the setting.
https://api.drupal.org/api/drupal/modules!system!system.module/function/system_settings_form/7
https://drupal.org/node/206761

function test_admin_settings() {
$form = array();
// Test output visibility settings.
    $form['display'] = array(
        '#type' => 'fieldset',
        '#title' => t('Display options'),
    );
    $form['display']['test_display_section_summaries'] = array(
        '#type' => 'checkbox',
        '#title' => t('Show summaries on administration sections.'),
        '#default_value' => variable_get('test_display_section_summaries', 1),
        '#description' => t('If unchecked, the summaries will still be visible on the <a href="@test-overview">reports</a> page.',
        array('@xray-overview' => url('admin/reports/xray'))
    ),
    );
    $form['display'][test_display_callback_function'] = array(
        '#type' => 'checkbox',
        '#title' => t('Show the page callback function on all pages.'),
        '#default_value' => variable_get('test_display_callback_function', 1),
    );
    $form['display']['test_display_form_id'] = array(
        '#type' => 'checkbox',
        '#title' => t('Show form ID in forms.'),
        '#default_value' => variable_get('test_display_form_id', 1),
    );
    return system_settings_form($form);
}