A problem that has perplexed users, and developers, since the start of the "Computer Age" has been handling input in multiple languages. The standard ASCII character set and the ANSI character set support at most 256 characters. This is enough for control codes, a..z, A..Z, 0..9, and extended european characters.

Unfortunately, this has inhibited the adoption of personal computers in many countries, most notably the Asian countries of Korea, China, and Japan.

In response, various input methods were created, from tablet input, to large multifunction keyboards. All of these were consolidated by Microsoft in a peice of software called the Microsoft Input Method Editor. This software is and has been available with each non-english version of windows, primarily in the Asian versions (most notably Chinese, Japanese, and Korean). The IME used by Windows ME, for instance, is the same as that used by Windows 2000. And each subsequent OS upgrade has upgraded the IME as well.

The IME works by handling focus interestingly. While the IME window can be interacted with, it does not steal focus from the active window. This allows the IME to know which program to send the data to.

It also adds a few menu items to the standard text context menu, allowing you to open an IME in just about any text box. All input is generated using the Shift-JIS encoding format (not Unicode).

The IME UI is complex, but features many powerful tools. The basic UI is a simple menu item that sits in the system tray. By clicking on it, you can select your input mode:
The indicator option changes the IME icon from a red/white pen to an indicative symbol of your mode. The IME Pad is where many of the extended tools for finding Kanji reside.
Full width Katakana are standard two byte characters. Full width ASCII are a special range of ASCII characters that take up 2 bytes, and are the same width as standard kana/kanji, so that the ASCII does not interrupt the monospaced behavior of the kanji. Half width Katakana is used by replacing the standard width extended european characters with half width kana (a codepage trick) that take up a single byte. Half width ASCII is standard ASCII.
Direct Input tells the IME to ignore all input.

Depending on your default settings, the menu items (and the entire UI) will appear in either the native language of your version of Windows or in Japanese.

The IME Pad

The IME Pad contains many features, such as a Bushu lookup, a Radical lookup, a stroke-count lookup, an on-screen keyboard, and a handwriting recognition section.

The bushu is a single radical lookup, under which all kanji with that character can be found.

Here you can select more than one radical. It's not all that different from the Bushu, except it lets you narrow your choices down a bit more.

Stroke count:
Lets you choose your kanji based on the number of strokes required to draw the character.

Using a mouse or a drawing tablet, you can draw the kanji as close as you can get, and the software will guess the character. It bases its decisition, from what I infer, on the number of strokes you apply and the direction you apply them in. Handy when you can't seem to find the character in the radical lookup.

Onscreen Keyboard:
The onscreen keyboard is multifunction, emulating a standard QUERTY keyboard, an alphabetical english keyboard, a hiragana/katakana swap keyboard (JIS Layout), a hiragana/katakana (50 kana layout, ordered by vowel), and an extended character input board for handling dates and times.