K2 is a Joomla component that enhances the Joomla features.
It replaces the management of articles with the K2 items. The categories can have many levels (like Joomla 2.5 and WordPress). The items can be tagged, have a featured image, attachments and custom fields (like in WordPress). A comment system is also included (in WordPress too).
All the K2 content can now be converted easily to WordPress with the Premium version and with the «K2 add-on».