The Ogham alphabet consists originally of twenty letters, 5 added at a later date. The original twenty letters each consist of from one to five straight lines or notches intersecting a stem line. The earliest surviving Ogham inscriptions are carved on standing stones with the edge of the stone forming the stem line. These stones are found mainly in Ireland, although others have been found throughout the British Isles. The script on them usually spells out the name of an individual and they are thought to be boundary markers.
There is also evidence for the magickal and divinatory use of the Ogham alphabet from the literature of medieval Ireland.
Historically the symbols were used for divination by the use of four Yew wands, possibly pentagonal in shape so an Ogham symbol could be inscribed onto each side. The wands would always fall with one corner pointing upwards and this would be the symbol which was read. The position the sticks fell in may also have been an important factor. Recently, the Ogham alphabet has been used for divination by inscribing it onto small wooden staves or onto discs of wood. One symbol is added to each piece and they are used in a similar way to the runes.