See: http://developer.apple.com/documentation/Carbon/Conceptual/UnderstandTextInput_TSM/tinptsm_intro/chapter_1_section_1.html

---

While new to Roman script users, input methods have been part of the Mac OS dating back to pre-OS 8 times (System 7.6, I think). They were initially designed to allow entry of Japanese, Korean and Chinese text, using software when a hardware keyboard would be impossible or inconvenient.

Visit System Preferences/International/Input Menu tab and turn on the Character Palette if you haven’t already discovered this (very cool) input method.

Inkwell is also an input method, but is “special” in that it’s UI is provided differently than keyboard-type input methods.