SQL Server Database Transaction Tutorials
A transaction is a group of SQL commands executed together as a single component of work to be accomplished. If all of these commands succeed, then a transaction is committed - the changes to the data are made final. If any of the commands within a transaction fail, then the entire transaction is cancelled, or in SQL Server terms, the transaction will be rolled back.
Transactions are one of the things that keep your data safe, but they're not necessarily easy to understand. Here's some help:
SQL Server Transaction Log Articles
Transactions are logged in a separate data file called a transaction log. Walk into any datacenter, pull the power cords out of a SQL Server, and when it boots back up, the data will almost always be safe. Transaction logs are the key to that safety.
SQLServerPedia Blog Entries About Transactions
These blog entries point out short tips or helpful resources on other web sites about transaction logs, log backups, and more: