It is difficult to analyze what the programming language is actually written to make the whole of Windows 10, but Rietschin guesses that perhaps 98% will be C or C ++.

Microsoft announces progress towards making the Rust programming language friendlier for Windows development. Written by Liam Tung, Contributing Writer May 10, 2021 at 4:05 a.m. PT.

Java is a popular programming language that every programmer should learn. ... The code is written in English for humans to understand, ... including Windows, Linux, Mac, and more. Java Code examples.