A version is a number assigned to a software package having a particular set of functionalities. The authors of the software or application keep on removing previous bugs & adding new features to the applications and the newer application is marked with a newer number called version. If there is a small change the version number is increased by a decimal point. If there is a larger change in the application, the version number is incremented by the whole number. Most of the applications have the feature to check if the higher version of that application is available on the internet. If the higher version of application is available on the internet, we can uninstall the lower version & install the higher version of the application. At times we need not uninstall the lower version of the application and some patch or driver is available installing which the application acquires the functionality of higher version & the application shows the version number of the higher version application. So a complete version of application is a complete software package which can be installed independently. An upgrade is not a complete software package which can work on its own.