A lot of new features have been added to PHP with PHP 5.4 and 5.5. Most of these features were originally part of the PHP 6.0 release, which had to be postponed as rewriting PHP to support Unicode did not go as planned. Unicode is an industry standard character encoding set that supports most of the world languages, unlike ASCII that only encodes the Latin alphabet. One prominent issue that the developers faced during rewriting languages for Unicode support was that it almost took twice the runtime memory to execute the scripts. A few new features that have been shipped with PHP 5.4 and 5.5 are the ability to monitor upload progress, multiple improvements to arrays, a built-in web server, the password hashing API, the generators, partial Unicode support, updates to closures, and the powerful traits. PHP 5.4 and 5.5 arrives with multiple updates that will help us execute scripts faster and use less memory.