The Ancient, Strange Coding Language that 95% of ATMs Use

TL;DR

COBOL still powers 95% of ATMs and $3 trillion in daily transactions because its legacy financial systems are too costly and complex to replace.

Key Points

• 1.COBOL was born in 1959–1960 as a universal, hardware-agnostic business language. The U.S. Department of Defense mandated COBOL compilers on all purchased machines, forcing industry adoption and spreading it across government, finance, and data-heavy sectors.
• 2.COBOL runs an astonishing share of modern financial infrastructure. By one estimate it handles $3 trillion in transactions daily, powers 80% of in-person credit card transactions, 95% of ATM transactions, and 40%+ of online banking systems — plus the oldest verified running program, a DoD defense-contract system.
• 3.COBOL was intentionally designed to read like plain English, making it unique among coding languages. Code lines are called 'sentences' ending in periods, keywords number in the hundreds vs. Java's 68, and arithmetic is written as 'ADD 5 TO 6' — prioritizing legibility for government and business users over mathematical conciseness.
• 4.Its English-like simplicity becomes a liability at scale, producing notorious 'spaghetti code.' Global variables and GOTO statements mean changing one line can break an entire million-line system, making maintenance extremely difficult for anyone who didn't originally write it.
• 5.A critical shortage of COBOL engineers now threatens these systems. Almost no one learns it today; maintenance relies partly on a group called the 'COBOL Cowboys' — roughly 600 veteran engineers — and the only solutions are training a new generation or undertaking the enormously expensive process of rewriting legacy systems from scratch.