The structure of Irish surnames
Irish surnames are common throughout the world, particularly in America, England and Australia. They have the peculiarity of often having two parts, rather than one, a legacy from the days when Gaelic was spoken throughout the land. Hereditary surnames were not used in Ireland prior to the tenth century; surnames were only used for a single generation. A man was known as 'son of', mac in Gaelic, his father. Thus Turlough, son of Art, was Turlough Mac Airt. Turlough's son Conor would be known as Conor Mac Turlough. Alternatively, if his grandfather was considered a more prominent figure, he would be known as 'grandson of', Ó in Gaelic. Thus Conor would be known as Conor Ó Airt, meaning Conor, grandson of Art. The apostrophe commonly seen in Irish surnames today is an Anglicanized version of the Gaelic accent, so that Ó became O': Ó Baoill became O' Boyle in English. Another common feature of Irish surnames is the prefix fitz, as in the names Fitzgerald & Fitzpatrick. This is a legacy from the Norman invasions of Ireland, and is a corruption of the French fils or 'son of'. Since Mac and Fit' have the same meaning they were interchangeable at one time.

Influences on surnames
Ireland was one of the first European countries to use fixed hereditary surnames. Many of these names show the strong ties and influence of the Catholic Church. The surname prefixes, Gil and Kil, are derived from the Gaelic giolla, meaning 'follower'. Therefore, Gilmartin was 'a follower of St. Martin'. Another prefix with religious intonations is Mul, taken from the Gaelic maol, meaning bald. This referred to the Irish monks, whose monasteries dotted the country. Other names are Anglicanized versions of Irish descriptions of character or personality: Reilly (brave), Quinn (intelligent), Kennedy (helmeted), and Sullivan (black eyed). Others indicate occupations: Falconer, Smith, Cooke, Taylor, Mason, Archer and Harper.

Further complications arose when the old Gaelic names were transposed into English. For example Carey, derived from the Gaelic O`Ciardha, became Carew or even Carr. From the start, Ireland was influenced from a variety of foreign invaders. Modern Irish surnames are the result of intermingling with Nordic, Anglo-Norman, Welsh, Scots and English for over a millennium. Many surnames are interpretations of these invaders homelands. For example, Walsh (Wales), Cusack (Cussac), Lyons (Lyons), and Joyce (Jose).  Clan and family remain the cornerstones of Irish society today. Irish people all over the world share these values, and encourage them in their own children. Irish identity is inextricably linked to ancestry and heritage, the past always an undeniable part of the present.