Мисля че тук е обяснено най-добре и на бг:
http://nau4i.me/index.php?option=com_content&view=article&id=60:-for&catid=34hp--&Itemid=60
http://nau4i.me/index.php?option=com_content&view=article&id=61:-while&catid=34hp--&Itemid=60
http://nau4i.me/index.php?option=com_content&view=article&id=64:-1&catid=34hp--&Itemid=60
http://nau4i.me/index.php?option=com_content&view=article&id=65:-2&catid=34hp--&Itemid=60
http://nau4i.me/index.php?option=com_content&view=article&id=66:2009-11-30-14-06-28&catid=34hp--&Itemid=60
http://nau4i.me/index.php?option=com_content&view=article&id=67:-foreach&catid=34hp--&Itemid=60