What is data journalism? I could answer, simply, that it is journalism done with data. But that doesn't help much.Both 'data' and 'journalism' are troublesome terms. Some people think of 'data' as any collection of numbers, most likely gathered on a spreadsheet. 20 years ago, that was pretty much the only sort of data that journalists dealt with. But we live in a digital world now, a world in which almost anything can be -- and almost everything is -- described with numbers.