a) Document Object Model Source: W3Schools – JavaScript HTML DOM 2 ... c) To get or set the HTML content of an element Source: Studytonight – innerHTML Events 1. b) A user or browser action Source: ...

For which languages does it work? The comments in prettify.js are authoritative but the lexer should work on a number of languages including C and friends, Java, Python, Bash, SQL, HTML, XML, CSS, ...