In this chapter, you have learned that all data access in SQL Server is done through transactions. Every transaction conforms to the ACID rules and can be defined explicitly to correspond to business transactions. Every explicit transaction should also implement an error handler to define under which circumstances SQL Server should roll back the transaction.
You have seen how SQL Server can isolate transactions from each other through locking and row versioning and how it is possible to implement the best level of isolation for your transaction through defining isolation levels. Also, you have learned how important it is to choose the right isolation level to minimize blocking and deadlock problems in databases.
Chapter 10 Quick Reference