Now that you have seen what transaction processing is, we need to look at why you would want to use it in developing your application. There were a number of reasons that became evident when looking at what transaction processing is. The ability to develop applications in a single-user mode, then use the transaction processing system to scale to hundreds or thousands of users is one reason. As a matter of course, the transaction processing system also provides the support for automatic rollback of transactions that did not complete successfully. There are other reasons for using transaction processing that become much more readily available to developers when working in a transaction processing system. These include the concepts of a three-tier application model, applications distributed across many systems, and the benefits of what is know as the ACID properties of transaction processing systems.