Transaction server
Software to allow working with transactions in a safe environment.
A transaction involves multiple parts which must be completed atomically, for example when paying someone from your bank the system must guarantee that the money is taken of your account and paid into the other persons account. It would simply be unacceptable for just one or the other action to take place.
This will mean ensuring that transactions are guaranteed, or that if a transaction fails the system can tell this has happened.
In the case of a transaction failing it can then be "backed out", which will mean that the system reverses all the actions that happened during the partial completion of the transaction.
A transaction server will comprise of a system providing the safety described above, and an enviroment where programs can be written to make use of these features. It will also have various connection protocols to allow it to connect to the backend databases of the company, and to the front end software (for example the computer of a telesales person or the web interface of an online bank).