Apple maybe an American company, but it ships its products all over the world. There are numerous countries whose main language is not English. Or it may be English but it may not be American English. I’ve found out the hard way that the Queen’s English is a different animal of sorts. It is a great feature of Mac OS X that you can set your language and text preferences without changing the whole system.
Fortunately, as with most global products, you can easily switch the default language of your Mac. That and some other settings can be configured through the Language and Text preference pane of your Mac.
To see and change your settings, launch open the System Preferences from the Dock. Among the different panes, select Language and Text. A window will open and you can configure the different settings.
Under the Language tab, you can select the default language being used by OS X and all your other tabs. If you most of your time on your Mac is spent typing or editing it might be useful to configure the Text tab. You can create auto-complete templates and shortcuts for symbols that you may otherwise have to find through the men. For example you may designate (c ) to automatically change to © the copyright symbol.
This doesn’t really apply to me but if you are bilingual and create documents in another language, you can configure the Text tab to spell check for that language. No, you do not have to change the default language of the system. You just add on the spell checking ability. So that means even if the system is English, it can still correct your Italian document.