<P> The foundation of PHP 7 is a PHP branch that was originally dubbed PHP next generation (phpng). It was authored by Dmitry Stogov, Xinchen Hui and Nikita Popov, and aimed to optimize PHP performance by refactoring the Zend Engine to use more compact data structures with improved cache locality while retaining near - complete language compatibility . As of 14 July 2014, WordPress - based benchmarks, which served as the main benchmark suite for the phpng project, showed an almost 100% increase in performance . Changes from phpng are also expected to make it easier to improve performance in the future, as more compact data structures and other changes are seen as better suited for a successful migration to a just - in - time (JIT) compiler . Because of the significant changes, the reworked Zend Engine is called Zend Engine 3, succeeding Zend Engine 2 used in PHP 5 . </P> <P> Because of major internal changes in phpng, it must receive a new major version number of PHP, rather than a minor PHP 5 release, according to PHP's release process . Major versions of PHP are allowed to break backward - compatibility of code and therefore PHP 7 presented an opportunity for other improvements beyond phpng that require backward - compatibility breaks, including wider use of exceptions, reworking variable syntax to be more consistent and complete, and the deprecation or removal of various legacy features . </P> <P> PHP 7 also introduced new language features, including return type declarations for functions, which complement the existing parameter type declarations, and support for the scalar types (integer, float, string, and boolean) in parameter and return type declarations . </P> <Table> Key <Tr> <Th> Color </Th> <Th> Meaning </Th> <Th> Development </Th> </Tr> <Tr> <Td> Red </Td> <Td> Old release </Td> <Td> No development </Td> </Tr> <Tr> <Td> Yellow </Td> <Td> Stable release </Td> <Td> Security fixes </Td> </Tr> <Tr> <Td> Green </Td> <Td> Stable release </Td> <Td> Bug and security fixes </Td> </Tr> <Tr> <Td> Blue </Td> <Td> Future release </Td> <Td> New features </Td> </Tr> </Table>

What is the meaning of .= in php