Creating MS SQL Server transaction log backup.

Transaction log backup is a backup for log files of a database .
Backing up the transaction log periodically to create a sequence of transaction log backups offers users the most flexibility in restoring databases.
By creating transaction log backups, a database can be restored to any point in time contained within the sequence of transaction logs, right up to the point of failure , because it is possible to back up the currently active transaction log even if the database is inaccessible.