There are a great many -ise/-ize words, and the generally held belief is that proper practise in English (as opposed to American) is to use the -ise form.
The broad myth is that the -ise forms stem from French and don't do as good a job of representing the pronunciation as the -ize forms. Then, the myth continues, the switch occurred to -ize forms in America in the same way as simplying neologisms such as "nite", "thru", "color", and so on were introduced, in one of those periodic attempts to reform English spelling.
https://en.wikipedia.org/wiki/English-language_spelling_reformOnly problem is, it's bollocks. The -ize forms are documented in English writing (as opposed to American) as early as the 15th century, far earlier than -ise forms which only cropped up 300 years later. This is why the Oxford University Press actually uses the -ize forms as standard:
http://blog.oxforddictionaries.com/2011/03/ize-or-ise/That said, there are a number of English verbs which must have an -ise ending in both English and American, because of their origin in other languages. These include words like "comprise", "promise", and "exercise". And there are still some words that take yet another form, namely -yse, including "analyse", although these are all spelled with -yze forms in American.
http://www.oxforddictionaries.com/words/ize-ise-or-yseOh, and then there's "programme" and "program": interesting rant by Richard Dawkins on that topic in one of his older books, and not in the way you'd imagine.
Finally, FWIW and the OED notwithstanding, I personally insist on the -ise forms. Because I'm like that.
