As a Joomla website owner, you probably already know the importance of keeping your site up to date.  This means both the plugins used in your site and even more importantly, the Joomla Core itself.

The below link shows the upgrade history, and you can check what version of Joomla you have from your Joomla Administrator page, under the System Information Tab.

Joomla Official Version History

https://docs.joomla.org/Category:Version_History