Here's the story. It's far more interesting than a simple ABC.
The early Celts originated a system of writing or signed communication. It's called Ogham.
The symbols were called after various trees and plants.
The symbols were cut into the vertical edge of a stone (from the bottom up) or into a piece of wood.
There are hundreds of Ogham stones in Ireland - mainly in the south western part. "Kilroy, son of Here" seems to be the basic message type carried by the markings.
The plants influence a system of writing. The symbols are scratched into stone. Technology progresses and the symbols are cut into pieces of wood. Later, people get the idea of
One of the symbols (the Q) is named 'Quert'
- as in QWERTY keyboards ??? - I've already talked about our prescient ancestors in the introduction to Tír na nÓg.
This Ancient Scripts page gives a good overview of the symbols themselves, with examples in three styles.
Credit is given to Curtis Clark for his ogham font.
The Four Pillars : Eloquence and Ogham has more information.
More images of ogham.
Everson Gunn Teoranta seem to be the people to see for resources (fonts and other matters) for minority cultures. They have many links to information on Ogham (as well as their own fonts).
If your interest is casual, don't let the lists of standards put you off. Dig a little and you'll find 'more relaxed' material.
This is also a good site for examples of Irish language texts.
Ogham has been a stong influence on the artist Patrick Ireland. His 9-part wall painting "The Ogham Cycle" is described and illustrated in the Sirius Arts Centre site.
Go to Tír na nÓg