Emoji used on these sites are based on the Unicode Standard 6 which offers 722 characters, some of them are mapped to other characters already existing while other emoji are encoded in seven different blocks.
Depending on your type of device (PC, Android, iPhone) and your type of browser (Internet Explorer, Chrome, Safari, Firefox,...) the emoji are typically shown differently.
The emoji over here are created dynamically to give all of you the same experience of great looking emoji independent of the viewing device. The only exception are the input fields which might look strange (typically empty black blocks) but it still works.
Emoji are smileys or ideograms originally used in Japanese electronic messages and webpages. Emoji means "picture" (e) plus "character" (moji).
The emoji dictionary is a fun project and creates a community to get people fluent in emoji. You can promote your own emoji translations and decrypt messages you get.
The page itself works on all available browsers on Android and iPhone, even though support for emoji in todays operating systems and mobile devices is not fully available.
A big thank you to the guys at EmojiOne who designed amazingly cool emoji symbols and a library to bring it to all of you - be it emojis on the PC, Android, iPhone or any other device.