AFAIR It is because a 30 years old rant in Usenet that defended spaces over tabs, but all their arguments were biased by the fact it was about LISP. It's impos

AFAIR It is because a 30 years old rant in Usenet that defended spaces over tabs, but all their arguments were biased by the fact it was about LISP. It's impossible to use anything but spaces in LISP without going mad, and the editors like emacs do a fantastic job formatting the s-expressions. So spaces are very superior to tabs for some languages. For languages with a syntax similar to C, it doesn't matter, the rant was taken out of context, and the rest is history. Whatever you use, make tabs and spaces visibles in your editor and never, ever, mix them up for indentation.