Organisation or organization? Believe it or not, this has recently been giving me some headaches.
The simple answer given by most people is that organization (like color and analyze) is American spelling, and organisation is British spelling. But it’s not that simple. It turns out that it depends on what flavour (or should that be flavor) of British spelling you’re using. In particular, if you are using Oxford spelling. Oxford spelling is the spelling used by the Oxford University Press. Now, according to Wikipedia:
“It can be recognized for its use of British spelling combined with the suffix -ize instead of -ise.”
“The spelling is favoured on etymological grounds, in that -ize corresponds more closely to the Greek root, -izo, of most -ize verbs.”
“The use of -ize instead of -ise does not affect the spelling of words ending in -yse, such as analyse, paralyse and catalyse, which come from the Greek verb λύω, lyo, not from an -izo verb.”
This may all be the case. However, I’d say the good folks in Oxford have created something of a problem for proles (slang for proletarians) like me, who aren’t trained in classical Greek. I doubt I’m alone in thinking that it’s quite a task to figure out, for any given word, whether its roots lie in the Greek ‘-izo‘, or ‘lyo‘.
What does this mean for you? I have adopted the simple solution. If there’s an ‘organization’ in the text, the rest of the text will use an American spelling. Otherwise, the ises have it.