What improvements and innovations have been introduced in the latest PHP releases?

The latest releases of PHP have introduced the following key improvements and innovations:

• Performance enhancements and engine optimization of the Zend Engine.
• Support for new syntactic constructs, such as improved types (union types, mixed, static return type).
• Addition of attributes (annotations) for metadata in code.
• Improved support for asynchronous programming and generators.
• New functions and extensions for working with databases, cryptography, and other areas.
• Improvements in the error and exception system.

For example, starting with PHP 8.0, union types appeared:

function foo(int|string $param) {
    // $param can be either int or string
}

These innovations make the language more modern, safe, and convenient for development.