A transaction is data modification that is performed on a database. A copy of the old and new state of each row affected by each data modification statement is written to the transaction log.
This means that if you begin a transaction by issuing the begin transaction command, realize you have made a mistake, and roll the transaction back, the database is restored to its previous condition.
However, if select/into bulkcopy database option is set to false, the default mode of writetext does not log the transactions. This prevents the transaction log from filling with the extremely long blocks of data that text, unitext, and image fields may contain. To log changes made with writetext, use the with log option.