SWIFT is the messaging backbone of international banking — it does not move money, but sends instructions between banks about how to move it. When you wire $10,000 to someone overseas, your bank sends a SWIFT message to their bank with transfer details. Over 11,000 institutions in 200+ countries use SWIFT.
SWIFT processes over 44 million messages per day. Each bank has a unique SWIFT/BIC code (like SBI's SBININBB). Despite its dominance, SWIFT is slow — cross-border transfers take 1-5 business days and cost $15-50 in fees. This has spurred alternatives: China's CIPS, Russia's SPFS, and India's UPI-based cross-border initiatives.
SWIFT became geopolitical news when Russia was partially disconnected from SWIFT in 2022 after invading Ukraine — effectively cutting major Russian banks off from the global financial system. Iran was also disconnected in 2012 and 2018. Being removed from SWIFT is considered the "nuclear option" of financial sanctions, isolating a country from international trade and finance.