Variable_get question default value in form So I am reading Drupal Development Pro 7 and have stumbled upon something I am a little bit unsure about to do with the variable_get function &amp; form element. I understand it retrieves a stored value from the database and the second parameter is a default value if it cannot find anything in the database matching that form element. 

My question is what does the second parameter do in this example below.

foreach($types as $node_type){
    $options[$node_type-&gt;type] = $node_type-&gt;name; //access the $node_type object and store specific properties from the node_type object in $options array
}

//Checkboxes on Form
$form['annotate_node_types'] = array(
    '#type' =&gt; 'checkboxes',
    '#title' =&gt; t('Users may annotate these content types'),
    '#options' =&gt; $options,
    '#default_value' =&gt; variable_get('annotate_node_types', array('page')), //when using the system_settings_form, the name of the form element must match the key of the variable_get ie $form[] = variable_get('$form[]', '') Always form_element name
    '#description' =&gt; t('A text field will be available on these content types to make user-specific notes.'),
);
The #default_value for a 'checkboxes' element must be an array rather than a single value (so you can have multiple default values selected).

All that code does is provide the default value wrapped in an array, so that it conforms to what the 'checkboxes' element type is expecting.