Words ending in -ize/-ise

Verbs in British English that can be spelled with either -ize or -ise at the end are always spelled with -ize at the end in American English:

apologizeapologize or apologise
organizeorganize or organise
recognizerecognize or recognise

The same is true of words that end in -ization or -isation in British English. In American English, they always end in -ization:

civilizationcivilization or civilisation
modernizationmodernization or modernisation

Grammar and usage