Every Magento version comes with strengths and weaknesses and upgrading your Magento to the latest version is the key to increase speed, Security problems and new extensions from which some should be compatible with your Magento’s older versions. For the upgrade, you need to check the current version first.
There are different options to find out:
- You can use free online tools to check the version where you just have to enter your website address.
- You can check the version using admin panel.
- You can check the version in the app/mage.php file of your Magento installation.
- You can either use command line by the code Mage::getEdition() that is to give you all the necessary information.
For detailed information, click here: https://www.magemonkeys.com/how-to-check-the-version-of-magento-store-1-2/