As written in the previous section, full backup establishes a baseline for more efficient backup strategies. In other words, at least one full backup must be created before we can start a backup transaction log. A transaction log backup is a consequencing backup that backs up all transaction log records from the last LSN, which is contained in any previous backup.
In other words, a full backup is a backup of state of the database while transaction log backup is a backup of additional changes. Using transaction log backup ensures that the recovery point objective (RPO) point to which the database could be restored, will be very close to the moment when the database was damaged.
Another important property of transaction ...
