New Classes and Interfaces
Other changes to extensions
Migrating from PHP 5.4.x to PHP 5.5.x
PHP Manual
New Methods
MySQLi
mysqli::begin_transaction()
mysqli::release_savepoint()
mysqli::savepoint()
Intl
IntlDateFormatter::formatObject()
IntlDateFormatter::getCalendarObject()
IntlDateFormatter::getTimeZone()
IntlDateFormatter::setTimeZone()
New Classes and Interfaces
Other changes to extensions
Migrating from PHP 5.4.x to PHP 5.5.x
PHP Manual