How to find post, page, tag, category and media ID in WordPress

<?php
// Add ID's to posts and pages overviews
add_filter('manage_posts_columns', 'posts_columns_id', 5);
add_action('manage_posts_custom_column', 'posts_custom_id_columns', 5, 2);
add_filter('manage_pages_columns', 'posts_columns_id', 5);
add_action('manage_pages_custom_column', 'posts_custom_id_columns', 5, 2);

function posts_columns_id($defaults){
    $defaults['wps_post_id'] = __('ID');
    return $defaults;
}
function posts_custom_id_columns($column_name, $id){
        if($column_name === 'wps_post_id'){
                echo $id;
    }
}

// Determine ID column width
add_action('admin_head', 'custom_admin_styling');
function custom_admin_styling() {
echo '<style type="text/css">';
echo 'th#wps_post_id{width:50px;}';
echo '</style>';
}

// Add ID to categories overview
function categoriesColumnsHeader($columns) {
        $columns['catID'] = __('ID');
        return $columns;
}

add_filter( 'manage_categories_columns', 'categoriesColumnsHeader' );

function categoriesColumnsRow($argument, $columnName, $categoryID){
        if($columnName == 'catID'){
                return $categoryID;
        }
}

add_filter( 'manage_categories_custom_column', 'categoriesColumnsRow', 10, 3);


// Show media ID in media library overview
function column_id($columns) {
    $columns['colID'] = __('ID');
    return $columns;
}
add_filter( 'manage_media_columns', 'column_id' );
function column_id_row($columnName, $columnID){
    if($columnName == 'colID'){
       echo $columnID;
    }
}
add_filter( 'manage_media_custom_column', 'column_id_row', 10, 2 );


// Show image dimensions in media library overview
function wh_column( $cols ) {
        $cols["dimensions"] = "Dimensions (w, h)";
        return $cols;
}
add_filter( 'manage_media_columns', 'wh_column' );
function wh_value( $column_name, $id ) {
    if ( $column_name == "dimensions" ):
    $meta = wp_get_attachment_metadata($id);
           if(isset($meta['width']))
           echo $meta['width'].' x '.$meta['height'];
    endif;
}
add_action( 'manage_media_custom_column', 'wh_value', 11, 3 );
?>

My name is Boris Hoekmeijer, I'm a webdesigner and graphic designer.
I sometimes run into a problem for which I have to find my own solution because Google just won't tell me. That's when I climb behind my mechanical keyboard, and fire away until a tutorial materializes. One of the great things about the web: we can all help each other!
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Cheers!