Common PHP File Extensions and Their Uses Explained

The Purpose of PHP File Extensions

PHP file extensions are used to identify files that contain PHP code so that the server can correctly parse and execute them. Different extensions serve various purposes and have evolved over time with PHP's development history.

Common PHP File Extensions

The most common PHP file extension used in web development is .php. However, other extensions may appear in certain environments or legacy systems:

• .php: The standard and most widely used PHP file extension. It indicates a text file containing PHP scripts that the server processes as PHP code.
• .php3: An outdated extension from the PHP 3 era. You may still find it in older applications but it is no longer recommended for modern development.
• .phtml: Used for embedding PHP code directly within HTML documents, often seen in template-based or legacy systems.

Other Less Common PHP Extensions

• .inc: Typically used for include files that contain reusable PHP code such as configuration or function libraries. These files should not be directly accessible through a browser for security reasons.
• .tpl: Commonly used in template engines like Smarty or Twig, designed for generating HTML or other dynamic content.

Choosing the Right PHP File Extension

The choice of PHP file extension mainly depends on the project structure and development conventions. The industry standard and best practice is to use .php consistently for all PHP scripts to ensure compatibility and clarity.

Conclusion

The variety of PHP file extensions reflects PHP's long history and flexible usage across different projects. While several options exist, the .php extension remains the safest, most universal, and officially recommended choice.