Be generous in what you accept, strict in what you provide.<p>Without that general principle the internet would <i>never</i> have got working. Even now, "standards" shift, and it's important that older sites don't simply stop working because of things that were once perfectly valid becoming slightly out-of-fashion.<p>Complexity is like a dead cat under the carpet. You can push it around all you like, but it will still be there, and someone still needs to deal with it.<p>It's just a shame that after a while it starts to smell, and the smell is hard to get rid of.