In more detail
It is a scrambled passage derived from a work by Cicero, "De finibus bonorum et malorum" (45 BC), and starts with "Lorem ipsum dolor sit amet, consectetur adipiscing elit". The words were cut, altered and reshuffled so that the result is not readable Latin, which is the point: the text has a natural-looking distribution of word and paragraph lengths but nothing to read. It spread through printers' type specimens and later desktop-publishing software. Replace it with real copy before publishing.
Why it matters
Placeholder text lets reviewers judge layout, typography and spacing without arguing about wording. But it can mislead. Real content is rarely as tidy: headlines run longer, names vary, translations are often noticeably longer than English, and some languages need different line breaks. A design that only works with lorem ipsum may break on real text. The other risk is leaving it live, where it looks unfinished and can be indexed by search engines, so search the finished site for "lorem ipsum" before launch.
Example
The conventional opening sentence is eight words long:
Lorem ipsum dolor sit amet, consectetur adipiscing elit
Need three paragraphs for a mock-up, or a fixed number of words to test a card layout? Generate them with the Lorem Ipsum Generator. For pictures that stand in for photos in the same way, use the Placeholder Image Generator.
Common confusion
It is filler, not a translation, and the words do not form a meaningful message. A Placeholder image is the picture equivalent. For text tools in general, see How Text Analysis and Editing Tools Work.