It is highly recommended to use the backup functionality of the app to create backups in regular time intervals. The backup file format is .dat and if you have chosen a password the backup file will be encrypted. It is also recommended to store all receive addresses in a text file or the like to be able to recover them manually, which is necessary under certain circumstances.
The backup file can be used to restore the wallet after a new installation of the app or after using the exit function.
The sole usage of a seed phrase as "backup" is no longer encouraged.