<Li> Quercus--compiles PHP into Java bytecode </Li> <Li> HipHop--developed at Facebook and available as open source, it transforms the PHP scripts into C++ code and then compiles the resulting code, reducing the server load up to 50% . In early 2013, Facebook deprecated it in favor of HHVM due to multiple reasons, including deployment difficulties and lack of support for the whole PHP language, including the create_function () and eval () constructs . </Li> <P> PHP is free software released under the PHP License, which stipulates that: </P> <P> Products derived from this software may not be called "PHP", nor may "PHP" appear in their name, without prior written permission from group@php.net . You may indicate that your software works in conjunction with PHP by saying "Foo for PHP" instead of calling it "PHP Foo" or "phpfoo". </P>

Write a note on php explain how php works in detail