SQL Server databases should be protected on a scheduled basis. A SQL database actually consists of two files; the database file (*.mdf) and a transaction log file (*.ldf). These files must match exactly for a backup copy of the database to restore properly.
more at http://databasenews24x7.blogspot.com/2009/05/protect-your-sql-server-databases.html
About dineshasanka
I have more than 15 years of experience in ICT inductry out of which 10 years in the SQL Server Database developments and designing.
These days more focus on BI / Datawhare house stuff in SQL Server