The green hue was incorporated in order to match the look of text on an old IBM CRT monitor. Then, looking to mix up the font, Whiteley combined these designs with Arabic numerals.

Munchies spotted a CNET report on the origins of the green code that waterfalls down the screen as the movie—and its successors—opens by way of Simon Whiteley.

Speaking with CNET in 2017, the code's designer, Simon Whiteley, revealed that the now-famous green code (also known as "digital rain" among fans) was inspired by one of his Japanese wife's cookbooks.

If you remember, the film featured a cascading green code that rained down the screen. Source of The Matrix’s Digital Rain That code has a surprising, rather weird, origin story behind it.