This is the “internet for banks,” basically. It’s a worldwide messaging system which banks use to exchange data and payment orders. If you need to transfer money from one bank to another, this message gets sent along the SWIFT Network.
SWIFT technically stands for “Society for Worldwide Interbank Financial Telecommunication.” It’s a cooperative, funded by banks around the world. It was founded in 1973, and the first message was sent in 1977.
SWIFT develops the data standards for banking. A SWIFT message complies with specific rules created by SWIFT to ensure banks can communicate. This has resulted in many issued ISO standards.
SWIFT can sometimes come into controversy, since a single network for international transactions means that it can be monitored. The US government, in particular, has been accused on over-reaching in their requests for information and their threat of sanctions if SWIFT doesn’t comply.