IT systems today are required to deliver the maximum performance with zero downtime and with maximum flexibility for developers and administrators. As developers, we all know that if performance of our applications is somehow lacking, then the cause of the slowdown must be in the database!
A major cause for performance problems inside database projects can be followed back to database design mistakes or to the limitations built in to the database engine to ensure data consistency for concurrent connections, or a mixture of both of these aspects.
Microsoft SQL Server adheres to the ACID theory. A simplified explanation of the ACID theory is that it describes how changes made to a database are required to fulfill four properties: Atomicity, Consistency, Isolation and Durability: