Ogham is an archaic Irish script that was used to write the Old Irish language. It is believed to have been in use from the 4th century AD to the 8th century AD, and consists of a series of strokes and notches cut into stone or wood. The script is composed of twenty letters, each representing a sound, and is written from left to right. Ogham is still used today as a form of divination and is also used in some modern Celtic art.