PHP 8.x introduces powerful features including property hooks, asymmetric visibility, pipe operators, constructor property promotion, named arguments, match expressions, and enums. Modern PHP development emphasizes design patterns like Repository, Service Layer, and DTOs for clean architecture. Comprehensive testing with PHPUnit covers both unit and feature tests using mocking and database factories. Performance optimization relies on OPcache configuration with JIT compilation and class preloading. These practices enable building maintainable, scalable, and performant PHP applications.