How to Create a Simple WordPress Plugin

Code

                    <?php            
                    /** 
                     * Plugin Name: Simple Plugin by AEZ-Tech 
                     * Plugin URI: https://www.aez-tech.site/how-to-create-wordpress-plugin/ 
                     * Description: Creating a Simple WordPress Plugin to display "Hello World!" on the frontend and has an admin page. 
                     * Version: 1.0.0 
                     * Author: AEZ-Tech 
                     * Author URI: https://www.aez-tech.site 
                    */ 
                    
                    // Prevent direct access to the file 
                    if ( ! defined( 'ABSPATH' ) ) { 
                    exit;} 
                    
                    // Displays "Hello World!" at the end of the content. 
                    function AEZ_hello_world_display() { 
                    echo '<p style="text-align: center; color: green; font-weight: bold;font-size: 30px;">     
                    Hello World<br/>Simple Plugin by AEZ-Tech</p>;}
                    
                    add_action( 'wp_footer', 'AEZ_hello_world_display' );
                    add_action( 'wp_body_open', 'AEZ_hello_world_display');
                    
                    // Add a new top-level admin menu page.
                    function AEZ_hello_world_admin_menu() {
                    add_menu_page(
                    'Simple Plugin',     // Page title
                     'Simple Plugin',    // Menu title
                    'manage_options',    // Capability required to access
                    'Simple-Plugin-by-AEZ-Tech',      // Menu slug (unique identifier)
                    'AEZ_hello_world_settings_page_content',      // Function to render the page content
                    'dashicons-smiley'// Icon URL or Dashicons class
                     );}
                    
                    add_action( 'admin_menu', 'AEZ_hello_world_admin_menu' );
                    
                    // Render the content of the admin settings page.
                    function AEZ_hello_world_settings_page_content() {
                    ?>
                    <div class="wrap">
                    <h1>Simple Plugin Settings</h1>
                    <p style="text-align: center; color: blue; font-weight: bold; font-size: 30px;"> 
                    Hello World <br/> Simple Plugin by AEZ-Tech</p>
                    </div>
                    <?php
                    }