COBOL is the programming language that underpins the entire financial system.
“Over 80% of in-person transactions at U.S. financial institutions use COBOL. Fully 95% of the time you swipe your bank card, there’s COBOL running somewhere in the background.“
“The second most valuable asset in the United States — after oil — is the 240 billion lines of COBOL”
The language is old (from the 1960s) and runs on huge machines (mainframes), yet it is extremely suited to the task of processing billions of transactions very fast.
