More accurate answer: coding.
The editing is standard for all. It knows the language so it can enable custom code highlighting and syntax rules. It really could be much smarter such as error messages when missing a semicolon like IDE's do to prevent lots of errors when you enter the code instead of waiting for you to compile.
Parsing / analysis for syntax highlighting shouldn't be much different than that done by languages themselves, though an implementation based on regex matching would have different "depth" than one tracking context (like the difference between spell- and grammar-checking).
I dropped a couple "lexical analysis" links here. If you follow the path, you can learn how to write your own stuff / get a feeling for what sort of analyzer / parser you're getting with various "IDEs".