If you are a power user of Android, you must have heard about backing up before flashing. Backup discussed there is nandroid backup.
According to a wiki on xda-developers, Nandroid is defined as
NANDroid is a de-facto standard directory structure for storing Android system backups. Nandroid is a utility, accessible through Recovery Mode, that allows you to backup your phone and restore to the exact condition at backup.
Performing full nandroid backups helps to restore even if your device is soft bricked. Nandroid backup backups OS, app data, and all other data that is required for booting. It does not backup personal media. Continue reading “How to perform nandroid backup?”