What lorem ipsum is, and why designers use it
Lorem ipsum is placeholder text: Latin-looking words with no meaning, used to show how a layout will look once real words are in it. The classic passage is adapted from a work of Cicero written in 45 BC, with words altered or removed until it reads as nonsense. That is the point. Because nobody can read it as a message, a reviewer looks at the type, the spacing and the rhythm of the page and not at the content.
Latin letters and word lengths also look much like ordinary English text. Words of mixed length, a few long ones and a mix of tall and round letters fill a column in a believable way, which a row of repeated words, or a line like text goes here, does not.
How the text is built here
Words are chosen at random from a list of about 120 Latin words, with the same word never used twice in a row. Each sentence has between 6 and 16 words, starts with a capital letter and ends with a full stop. Sentences of 6 or 7 words have no comma, those of 8 to 11 words have none or one, and those of 12 words or more have one or two. Paragraphs are made of 2 to 9 sentences, depending on the length you choose.
With Start with the classic opening on, the first sentence of the first paragraph is exactly the traditional one. In word mode, it begins with the first words of that sentence, so ten words gives Lorem ipsum dolor sit amet consectetur adipiscing elit sed do.
The generator uses a seeded random sequence, so the text only changes when you press Generate new text. If you change the count or the format, the beginning of the text stays the same.
When placeholder text helps, and when it misleads
It helps for early layouts and for testing how a template copes with long and short blocks of text. It misleads when the real content turns out to be different: real headings are rarely as even as placeholder paragraphs, real text has lists, names and numbers, and a language with longer words or another script (German, Arabic, Japanese) lays out differently from Latin.
Placeholder text should never reach a live page. Visitors get nothing from it, and screen readers read it aloud as if it were a language. Replace it with real copy, and test the design with real examples of your longest and shortest content.
Using the HTML output
HTML output wraps each paragraph in a <p> tag, one per line, so you can paste it straight into a page, an editor or a template. In sentence and word mode, the text is one paragraph, so it comes out as a single <p> element. The text contains only letters, commas and full stops, so no characters need escaping.