Ford Prefect (also called Ix) is a good friend of the an ordinary Earthman named Arthur Dent who knew him for several years and believed him to be "an out of work actor from the town of Guildford" in Surrey. Ford reinforced that
impression by carrying around scripts of plays he is supposed to be auditioning for; when the Earth is about to be demolished, he finally throws these scripts away.) However, Ford is actually from a small planet somewhere in the vicinity of Betelgeuse, and had originally only come to Earth to do some research for an article he was writing on it for the Guide.
Ford came to Earth for a week, and got stuck there for fifteen years, departing only when a fleet of Vogon constructor ships appear, taking Arthur Dent with him. Ford is the source of much explanation of the weird universe that Arthur finds himself in; for example, the importance of knowing where your towel is, sticking a fish in your ear, and why the greatest cooks in the universe cook such bad food on Vogon spaceships. Ultimately, however, his personal mission is to find a nice party and get incredibly drunk.
Name
Although Ford had taken great care to blend into Earth society, he had "skimped a bit on his preparatory research," and thought that the name "Ford Prefect" would be "nicely inconspicuous." Ford "had simply mistaken the dominant life form." The Ford Prefect was, in fact, a British car manufactured in the 1950s. When he first arrived on Earth, Ford was almost run over while attempting to greet a blue Ford Prefect. He was saved by Arthur and this is how the pair meet.
First birth name
Ford's original name is "only pronounceable in an obscure Betelgeusian dialect" which was almost wiped out by the "Great Collapsing Hrung Disaster of Gal./Sid./Year 03758," a mysterious catastrophe which took place on the planet of Betelgeuse Seven and which Ford's father was the only man to survive. Ford never learned to pronounce his original name, which was a matter that caused his father to die of shame (which is still a terminal disease in some parts of the Universe). At school, he was nicknamed "Ix," which translates as "boy who is not able satisfactorily to explain what a Hrung is, nor why it should choose to collapse on Betelgeuse Seven."
Despite all this, his semi-cousin with whom he shares three of the same mothers Zaphod Beeblebrox addresses him as "Praxibetel Ix," then introduces him by saying "This is my semi-cousin, Ix...Excuse me, Ford." Just before arriving on Earth he registered his new name officially at the Galactic Nomenclaturoid Office, where they had the technology to unpick his old name from the fabric of space/time and thread the new one in its place, so that to all intents and purposes his name had always been and would always be Ford Prefect."