The Old English Latin alphabet began to replace the Runic alphabet in the 8th century, due to the influence of Celtic Christian missionaries to the Anglo-Saxon kingdoms. The orthography of Old English – which was entirely handwritten in its own time – was not well standardized, though it did not use all the Latin letters, and included several letters not present in the modern alphabet. When reprinted in modern times, an overdot is occasionally used with two Latin letters to differentiate sounds for the reader: