Every day we perform transactions. A transaction is an interaction that involves an exchange; this could be monetary, information, service requests or other information. In addition, all the steps in a transaction have to happen or none at all. Quite often the first thing that comes to mind when transactions are mentioned are monetary exchanges, like the transfer of funds from one account to another or the use of automatic teller machines. The one thing that all transactional systems have in common is the requirement to maintain the integrity of the information. You do not want to transfer funds from your bank account to another bank only to find that the money has been lost in the ether.

Information regarding business transactions used to be kept in written ledgers; this provided a form of indelible record which could be audited and easily (though painfully) accounted for. It also used to take some time to perform the transfer of funds—on the order of days. This was fine for relatively small volumes of transactions. Nowadays in the hectic bustle of the modern capitalist world, we can easily see millions of transactions taking place on a daily basis within just one institution. The information for these transactions is stored within databases and passed between systems electronically over networks. While this is more efficient than the written method, it is also more volatile.