SQL Server

Transaction Log
This records all transactions and database changes made by each transaction and must be truncated regularly to prevent it from becoming full.

The transaction log is truncated after a log backup as long as a checkpoint has occurred since the previous backup. If the recovery model is set to simple, this are truncated after a checkpoint.

Truncating the log doesn't reduce the disk space used - you will need to perform a shrink of the log file to reduce the file size. This can be achieved using SQL Server Management Studio using the right-click option Tasks > Shrink > Files.

The log isn't always truncated successfully and there are a few reasons why this may be. Run the following query to find why the log is not being truncated:

Check the following in notes to ensure it is fully correct

SELECT ???, log_reuse_wait, log_reuse_wait_desc FROM sys.databases;

Generally, this transaction log should never be deleted or moved.