What is reinstallation?
A fresh installation refers to the installation of a software package that has completely deleted the previous version. The alternative to reinstalling is to upgrade, which preserves parts of the original software and does not remove it.
When reinstalling an operating system (operating system), the hard disk must be formatted. This means that all partition data will be lost and all data must be backed up on an external device. The process should then perform the installation, reinstall all applications and copy all data.
Since this process can be time consuming, it is a subjective judgment whether the extra time is worth it. In theory, there shouldn't be a problem with upgrades. In practice, new installations can be the only way to install an installation.
English 
German 