OGHAM ALPHABET (or Celtic tree alphabet) is an old writing system (Old Irish spelling, pronounced [ˈoɣəm] or Modern Irish spelling, pronounced [ˈoːm]). It was used mainly to write Primitive and Old Irish. It was inscribed on stone monuments throughout Ireland, particularly Kerry, Cork and Waterford, and in England, Scotland, the Isle of Man and Wales, particularly in Pembrokeshire in south Wales, where you can still find many of them. Over 400 known examples of ogham stones and fragments of various shapes and sizes have survived, each with its own unique biography or story.
This writing system or script was created for an early form of the Irish language and our earliest ogham inscriptions on stone are approximately dated on linguistic grounds to between the 4th and the 7th century AD.
Ogham generally reads upwards, from the bottom to the top. There are many varieties of Oghm alphabet, but this is the oldest one.