The purpose of lorem ipsum is to create a natural looking block of text (sentence, paragraph, page, etc.) that doesn't distract from the layout. A practice not without controversy, laying out pages with meaningless filler text can be very useful when the focus is meant to be on design, not content.

“Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem.”

So how did the classical Latin become so incoherent? According to McClintock, a 15th century typesetter likely scrambled part of Cicero's De Finibus in order to provide placeholder text to mockup various fonts for a type specimen book.