When building a website with PHP, understanding which modules are available on your hosting server is crucial. PHP modules are extensions that add specific functionalities to the core PHP language, enabling features like database connectivity, image processing, and encryption.

Most standard hosting plans include a comprehensive set of pre-installed modules. You can check the active modules by creating a simple PHP file with the code <?php phpinfo(); ?> and accessing it via your browser. The output will display a detailed list under the "Configure Command" and "Additional .ini files parsed" sections.

Commonly installed essential modules include:

• MySQLi / PDO_MySQL: For connecting to MySQL databases.
• cURL: For transferring data with various protocols.
• GD Library: For dynamic image creation and manipulation.
• OpenSSL: For secure socket layer and transport layer security.
• mbstring: For handling multi-byte strings (essential for non-Latin characters).

If your application requires a module that is not installed, you should contact your hosting support. Many hosts allow you to enable or disable modules via your control panel (like cPanel's "Select PHP Version" tool) or can install them upon request. Always verify module compatibility with your PHP version and scripts to ensure smooth website operation.