HHVM

HHVM stands for HipHop Virtual Machine. It is an open-source virtual machine for executing programs written in PHP and Hack. Developed by Facebook (now Meta), HHVM was initially created to improve the performance of Facebook's PHP codebase. It achieves this by using a just-in-time (JIT) compilation approach, which translates PHP code into optimized machine code during runtime, rather than relying solely on traditional interpretation.

HHVM supports both PHP and Hack, a dialect of PHP developed by Facebook that adds static typing and other features to improve code quality and performance. The virtual machine is designed to be highly scalable and efficient, making it suitable for large-scale web applications. It includes its own garbage collector and just-in-time compiler, contributing to its performance benefits.

While HHVM was widely adopted by many companies and projects, its development focus has shifted over time. Meta has increasingly moved its own PHP projects to use a standard PHP interpreter, particularly PHP 7 and later versions, which have also seen significant performance improvements. This has led to a reduction in ongoing development and community support for HHVM. However, it remains available and can still be used for projects that require its specific features or performance characteristics.