Lingua Franca of mages and magic
Draconic is the Lingua Franca of magic, and almost all arcane and psionic writing and research is written in this language. Though it is possible to learn spellcasting without it, a wizard who does not speak Draconic is about as rare as an Ecclesian priest who does not speak Sanctis.
A dialect of Draconic known as Yipyak is spoken by Kobolds. Kobolds do not read or write and as such do not use the Draconic Syllabary.
Draconic Syllabary
Draconic is written with a large syllabary which has a character representing each syllable, totaling exactly 15.831 distinct symbols. However, these symbols follow specific rules, which once mastered make them much easier to interpret - thus, a Draconic reader need not memorize all symbols, as they can deduce what syllable is intended from the structure of the character.
One disadvantage of the language is that it is very unforgiving of sloppy handwriting. Mages who sent their apprentices out with shopping lists are encouraged to write things up neatly, lest they end up with an Leg of Folding instead of a Bag of Holding.