To properly display the text you will need to choose a font that is loaded on your system or device. The font list groups standard fonts for Mac (Snow Leopard/Lion) and Windows7/8, and free Google fonts. Note that the web fonts aren't guarranteed to work on every system/device. This typically arises because the font relies on rendering algorithms provided by the operating system. See more information about standard OS fonts in Mac and Windows.
You can also add codepoints and escapes via the "Add codepoint" field (hit return to add to the output field). You can also paste text into the output field to get information about it. Use the yellow boxes to set preferences or search. Regular expressions are allowed when searching – for example, to find characters with the word KA in their name, enter \bka\b, or the short form :ka:.