What is a database transaction?

Question

Can someone provide a straightforward (but not simpler than possible) explanation of a transaction as applied to computing (even if copied from Wikipedia)?

Answer 1

http://en.wikipedia.org/wiki/Database_transaction
http://en.wikipedia.org/wiki/ACID
ACID = Atomicity, Consistency, Isolation, Durability

When you wish for multiple transactional resources to be involved in a single transaction, you will need to use something like a two-phase commit solution. XA is quite widely supported.