An Overview of Traditional Recovery
As with all relational database systems, SQL Server guarantees the durability of data by implementing crash recovery. Durability in the acronym ACID which refers to the characteristics of transactions in relational databases means that we can be assured that if the database fails suddenly, our data is safe.
SQL Server implements this capability using the transaction log. Changes made by all Data Manipulation Operations in SQL Server are captured in the transaction log before being applied to data files (through the checkpoint process) in case it’s needed to roll back or roll forward.