Historians have traditionally described the work as the first example of a biography of a European king. The author tried to imitate the style of that of the ancient Roman biographer Gaius Suetonius Tranquillus, who is most famous for his Lives of the Caesars. Einhard's biography used especially the model of the biography of Emperor Augustus, the first emperor of the Roman Empire.
The date of the work is uncertain, and a number of theories have been put forward. The inclusion of Charlemagne's will at the end of the work makes it fairly clear that it was written after his death in 814. The first reference to the work, however, comes in a letter to Einhard from Lupus of Ferrieres, which is dated to the mid-9th century. Dates have been suggested ranging from about 817 to 833, usually based on interpretations of the text in the political context of the first years of the reign of Louis the Pious and Louis's attitude to his father. No theory has yet emerged as an obvious frontrunner, and it is likely that debate will continue.
Einhard's book is about intimate glimpses of Charlemagne's personal habits and tastes. He occupied a favoured position at Charlemagne's court so he had inside information. Einhard received advanced schooling at the monastery of Fulda sometime after 779. He was an exceptional student and was quite knowledgeable. The word was sent to Charlemagne of Einhard's expertise. He was then sent to Charlemagne's Palace School at Aachen in 791. Einhard then received employment at Charlemagne's Frankish court about 796. He remained at this position for twenty some years. Einhard's book was expressly intended to convey his appreciation for advanced education. He wrote his biography after he had left Aachen and was living in Seligenstadt.
Einhard's position while with Charlemagne was that of a modern minister of public works so he had intimate knowledge of his court. Einhard was also given the responsibility of many of Charlemagne's abbeys. It used to be suggested that Einhard's wife, Emma, was a daughter of Charlemagne; that can generally be disregarded as a twelfth-century fabrication, however, since there is no proof.
Most biographies of the Middle Ages related only good deeds of their subject, with many embellishments to improve their subject. Einhard's biography, however, is considered, for the most part, to be a trustworthy account of Charlemagne's life. It is considered an excellent account of earlier Medieval life. Despite Einhard's limitations, since it was his first attempt at a major writing, the British historian Thomas Hodgkin said, "almost all our real, vivifying knowledge of Charles the Great is derived from Einhard, and that the Vita Karoli Magni is one of the most precious literary bequests of the early Middle Ages."