What is a plugin?
A WordPress plugin is a package of PHP, assets and configuration that adds or modifies functionality without changing the core platform. It is the recommended way to extend WordPress cleanly and keep updates safe.
Prerequisites
To build a plugin, you need:
- A working local WordPress install
- Basic PHP and WordPress API knowledge
- Editor with syntax highlighting
Plugin boilerplate
Create a new folder inside wp-content/plugins and add a PHP file with plugin metadata.
<?php
/*
Plugin Name: Hello Custom Plugin
Description: My first plugin.
Version: 1.0
Author: Ashutosh Rajbhar
*/
Hooks
Hooks let your plugin connect to WordPress lifecycle events. Use add_action() and add_filter() to run code where it matters.
function ashutosh_plugin_notice() {
echo '<!-- Plugin active -->';
}
add_action('wp_footer','ashutosh_plugin_notice');
Shortcodes
Shortcodes allow content editors to embed plugin output directly within pages and posts.
function welcome_shortcode() {
return '<h2>Welcome to the site!</h2>';
}
add_shortcode('welcome', 'welcome_shortcode');
Settings API
For configurable plugins, use the Settings API to store options and create an admin settings page.
function my_plugin_menu() {
add_options_page('Plugin Settings', 'Custom Plugin', 'manage_options', 'custom-plugin', 'my_plugin_settings_page');
}
add_action('admin_menu', 'my_plugin_menu');
Security
Follow these security best practices:
- Validate and sanitize all input
- Escape output with
esc_html()or equivalent - Check capabilities with
current_user_can() - Protect forms using nonces
- Prevent direct access by checking
ABSPATH
Recommended file structure
my-plugin/
my-plugin.php
readme.txt
assets/
includes/
languages/
Testing
Test your plugin on activation, deactivation, URL generation, and UI flows. Verify form submission, shortcode rendering, and settings persistence.
Deployment
Package your plugin as a ZIP file, include proper readme documentation, and publish to the WordPress plugin directory or deliver the ZIP to the client.