PHP is a popular server-side programming language that has gone through several major versions over the years. Here are the major versions of PHP:

1. PHP 1 (1995): The original version of PHP, often referred to as “PHP/FI” (Personal Home Page/Forms Interpreter). It was a simple scripting language for building dynamic webpages.

2. PHP 2 (1997): A more mature version of PHP with improved syntax and functionality. It added support for external libraries, which allowed developers to incorporate additional functionality into their PHP scripts.

3. PHP 3 (1998): Introduced a complete rewrite of the PHP engine, making it faster and more reliable. It also added support for object-oriented programming features.

4. PHP 4 (2000): A major update that brought significant improvements to performance and functionality. It introduced features like the Zend Engine, which improved performance significantly, and added support for sessions and output buffering.

5. PHP 5 (2004): Another major version that introduced significant changes to the language. It added support for object-oriented programming with a more robust object model, along with new features like exceptions, interfaces, and visibility modifiers. It also introduced the PHP Data Objects (PDO) extension for database access.

6. PHP 7 (2015): A major release that focused on performance improvements and language enhancements. It introduced the Zend Engine 3.0, which resulted in significant performance gains. It also introduced new language features like scalar type declarations, return type declarations, and anonymous classes.

7. PHP 8 (2020): The latest major release of PHP, which brought several new features and performance improvements. It introduced a new Just-In-Time (JIT) compiler for improved performance, along with new language features like union types, named arguments, and attributes. It also introduced the nullsafe operator for safer and more concise null checking.

Each major version of PHP has introduced new features, performance improvements, and bug fixes to make it a more powerful and reliable programming language. It’s important to note that older versions of PHP may no longer receive security updates, so it’s recommended to use the latest stable version whenever possible.