// Actions: side effects (send email, save data, enqueue assets)
add_action( 'init', 'acme_register_post_types' );
add_action( 'wp_enqueue_scripts', 'acme_enqueue_assets' );
add_action( 'admin_menu', 'acme_add_admin_page' );

// Filters: modify and return a value
add_filter( 'the_content', 'acme_append_cta' );
add_filter( 'excerpt_length', 'acme_custom_excerpt_length' );

// Default priority is 10, default accepted args is 1
add_filter( 'the_title', 'acme_modify_title', 10, 2 );

function acme_modify_title( $title, $post_id ) {
    // Always declare the correct number of parameters
    return $title;
}

// Remove a function callback
remove_action( 'wp_head', 'wp_generator' );

// Remove with matching priority
remove_filter( 'the_content', 'acme_append_cta', 10 );

// Remove an object method (must be same instance)
remove_action( 'init', array( $instance, 'init' ) );

// Plugin hooks should be prefixed and use underscores
do_action( 'acme_before_render', $context );
$value = apply_filters( 'acme_output_format', $default, $post );

// Dynamic hooks: prefix the static part
do_action( "acme_process_{$type}", $data );

// BAD - separate escape and translate
echo esc_html( __( 'Hello', 'acme-plugin' ) );

// GOOD - combined function
echo esc_html__( 'Hello', 'acme-plugin' );

// BAD
printf( __( '%s: %s', 'acme-plugin' ), $label, $value );

// GOOD
/* translators: 1: field label, 2: field value */
printf( __( '%1$s: %2$s', 'acme-plugin' ), $label, $value );

// BAD - direct output
echo '<script src="my-script.js"></script>';
echo '<link rel="stylesheet" href="my-style.css">';

// GOOD - proper enqueue
function acme_enqueue_assets() {
    wp_enqueue_script(
        'acme-main',
        plugin_dir_url( __FILE__ ) . 'js/main.js',
        array( 'jquery' ),
        '1.2.0',
        true  // in_footer
    );
    wp_enqueue_style(
        'acme-styles',
        plugin_dir_url( __FILE__ ) . 'css/styles.css',
        array(),
        '1.2.0'
    );
}
add_action( 'wp_enqueue_scripts', 'acme_enqueue_assets' );

// BAD - missing version, missing in_footer
wp_enqueue_script( 'acme-main', $url );

// GOOD
wp_enqueue_script( 'acme-main', $url, array(), '1.0.0', true );

function acme_admin_assets( $hook ) {
    if ( 'toplevel_page_acme-settings' !== $hook ) {
        return;
    }
    wp_enqueue_style( 'acme-admin', ... );
}
add_action( 'admin_enqueue_scripts', 'acme_admin_assets' );

function acme_frontend_assets() {
    if ( ! is_singular( 'acme_portfolio' ) ) {
        return;
    }
    wp_enqueue_script( 'acme-portfolio', ... );
}
add_action( 'wp_enqueue_scripts', 'acme_frontend_assets' );