There are more than 400 known orthodox Ogham inscriptions. These are Ogham inscriptions on stone recording the names of individuals, sometimes accompanied by their parentage and/or tribal affiliation, as opposed to later 'scholastic' Oghams, which derive from the manuscript tradition and do not descend directly from orthodox Ogham. Orthodox Ogham stones appear to have primarily served as memorials and/or boundary markers as well as indicators of land ownership. Possible associations between the commemorative function of Ogham stones and actual burials, and how these may have changed over time or geographical area, is an ongoing area of study. The inscriptions themselves were usually carved along the natural edge of the stone, generally starting at the bottom left-hand side of the face and reading upwards, across the top and down the right-hand side (up-top-down). However, there is a good deal of variation in this pattern, such as upward readings on both edges (up-up, e.g. CIIC 146. Ballineanig, Co. Kerry).
Ogham inscriptions are found in most counties in Ireland, but there is a marked concentration in the south-west, in counties Kerry, Cork and Waterford. Kerry alone has approximately 1/3 of the total and the barony of Corca Dhuibhne on the Dingle peninsula has the highest concentration with approximately 60 Ogham stones originating in this area. Outside of Ireland Ogham stones are also found in the areas where the Irish settled, such as Wales, the Isle of Man, Devon and Cornwall, and Scotland, although most of the Scottish oghams appear to be in Pictish or Old Norse. The distribution of Ogham inscriptions would seem to suggest that the practice originated in the south-west of Ireland. Furthermore, the fact that later inscriptions are also found in high numbers here suggests that this area remained a focal point for Ogham to the end of the tradition. The physical condition of the Ogham inscriptions varies considerably with many partially illegible. This is frequently owing to the location of the inscription on the vulnerable edge of the stone and to the re-use of Ogham stones in souterrains or other constructions. Indeed, Ogham stones are quite frequently found re-used, primarily in souterrains (over 40% of the total in Ireland), which is particularly common in Co. Cork. More than 40% of Ogham stones are found at or near ecclesiastical sites, although it can often be difficult to determine whether or not the find site was the original site.
The inscriptions very simply consist of names of individuals in the genitive case with a governing word, perhaps 'stone (of ...)' or 'memorial (of ...)', to be understood (cf. Roman-alphabet inscription CIIC 1. LIE LUGUAEDON... 'stone of Lugáed...', Inchagoill Island). Sometimes the father's name and/or tribal affinity is added. Occasionally the station in life is given, for example QRIMITIR 'priest' (deriving from Latin presbyter) on CIIC 145. Arraglen. There are a number of formula words that appear, the most frequent being MAQQI, genitive of *maqqas 'son'. Tribal affiliation is expressed by AVI (gen. of *awias 'grandson, remote descendant') or MUCOI ('posterity/tribe'), followed by the name of the eponymous ancestor. Other less frequent formula words include ANM 'name/inscription', KOI 'here' (corresponding to HIC IACIT on British inscriptions), CELI 'companion, client'.
Identification with any degree of certainty of the personal names inscribed on Ogham stones is not an easy task. This is mainly because they date from a period prior to which contemporary historical records began to be written, i.e. between the fifth century (or possibly even the fourth) and the seventh century AD, and so our knowledge of the period and the people who lived in it is very limited. McManus gives just one reliable identification from a British inscription. Guo(r)tepir, king of Dyfed, who died in the mid sixth century, appears to be commemorated in an inscription (CIIC 358) in both Latin script (MEMORIA VOTEPORIGIS PROTICTORIS) and Ogham (VOTECORIGAS). The person commemorated on CIIC 40. Painestown has more recently been identified with a Mac-Cáirthinn of a Leinster poem who was an Uí Enechglais king of Leinster and Tara.