XML’s tenth birthday is coming up next spring; here’s my sound-bite on What It All Means. XML is the first successful instance of a data packaging system that is simultaneously (human) language-independent and (computer) system-independent. It’s the existence proof that such a thing can be built and be useful. Is it the best choice for every application? Is it the most efficient possible way to package up data? Is it the last packaging system we’ll ever need? Silly questions: no, no, and no. JSON is already a better choice for packaging up arrays and hashes and tuples. RNC is a better choice for writing schema languages. A classic Unix-flavor file containing ordinary lines of ordinary text is the best choice of all, whenever you can get away with it. XML’s still a decent option, probably the best, for interchanging things that are (at least in part) meant to be read by humans. It could be improved. It might be replaced. Wouldn’t surprise me, either way.