SQL Server backup and restore operations occur within the context of the recovery model of the database. Recovery models are designed to control transaction log maintenance. A recovery model is a database property that controls how transactions are logged, whether the transaction log requires (and allows) backing up, and what kinds of restore operations are available. Three recovery models exist: simple, full, and bulk-logged. Typically, a database uses the full recovery model or simple recovery model. A database can be switched to another recovery model at any time.
1- Simple
No log backups.
You can recover only to the end of a backup. Automatically reclaims log space to keep space requirements small, essentially eliminating the need to manage the transaction log space. For information about database backups under the simple recovery model, see Full Database Backups (SQL Server).
Operations that require transaction log backups are not supported by the simple recovery model. The following features cannot be used in simple recovery mode:
- Log shipping
- AlwaysOn or Database mirroring
- Media recovery without data loss
- Point-in-time restores
2- Full
You can recovery point in time.
Requires log backups.
No work is lost due to a lost or damaged data file.
3- Bulk-logged
You can recover only to the end of a backup.
Requires log backups.
An adjunct of the full recovery model that permits high-performance bulk copy operations.
Reduces log space usage by using minimal logging for most bulk operations.
Source : Microsoft Offical Documents