In Week 9 of the IBM Full-Stack JavaScript Developer track, I stepped back from tutorials and asked a different question: what is the internet actually running on?

The answer isn’t the framework that trended on X this morning. It’s older, quieter, and far more stubborn.

COBOL: the 67-year-old that moves your money. Created in 1959, COBOL is still widely estimated to sit behind about 95% of ATM transactions and 80% of in-person banking transactions, with some 220 billion lines in production and around $3 trillion in commerce a day. One example: back in 2012, Bank of New York Mellon reported maintaining 112,500 COBOL programs, about 343 million lines of code. The catch is a talent gap. Universities largely stopped teaching it decades ago, and banks are now experimenting with AI tools to help maintain and modernize it.

PHP and WordPress: the web’s workhorse. PHP is used by about 70% of websites whose server-side language is known.…