On widows and orphans

An orphan is the first line of a paragraph stranded at the bottom of a page or column, with the rest of the paragraph carried over to the next. A widow is the reverse: the last line of a paragraph, often a short one, left alone at the top of a new page. Neither is wrong, exactly. Both are just uncomfortable to look at, and once you've learned to see them, you can't stop.

The names are older than most style guides admit, and slightly morbid on purpose — a line cut off from the family it belongs to. That's a good way to remember what's actually wrong with them: it's not the line count, it's the severed relationship. A reader's eye tracks a paragraph as a shape, and a widow or orphan breaks that shape at exactly the moment the reader has to turn a page, which is the worst possible moment to lose the thread.

Why they still happen

Justified, hyphenated print runs eliminated a lot of this by having real control over line breaks. On the web, they creep back in constantly, because a browser reflows text at every viewport width and doesn't know or care where a paragraph's shape gets awkward. A heading that fits perfectly at 1200 pixels wide can leave one orphaned word stranded on its own line at 780.

CSS finally has a real answer: orphans and widows properties control the minimum number of lines that must be left before or after a break, and text-wrap: pretty (where it's supported) goes further, balancing whole paragraphs to avoid single-word last lines entirely. Neither fixes everything — they're guidance for the browser's line-breaking algorithm, not guarantees — but both are better than the old trick of manually inserting a non-breaking space between the last two words of every paragraph and hoping the layout never changes.

The rule of thumb

If the last line of a paragraph is one short word on its own, or the first line of a new section is orphaned at a column break, fix it — even if that means rewording a sentence rather than reaching for markup. A paragraph should end on a line that looks like it was allowed to end there, not one that got cut off mid-thought by the shape of the page.