In typesetting terms, “widows” and “orphans” are lines at the end or beginning of a paragraph that are separated from the rest of the paragraph by a page break. If you think widows and orphans in your Word document are distracting, you can enable a setting that prevents them.
So, which is which? A widow is the last line of a paragraph that appears by itself on the following page and an orphan is the first line of a paragraph that appears by itself at the bottom of a page. You may see some disagreement online about these definitions, but the Chicago Manual of Style uses these definitions. Widows and orphans also occur at the ends and beginnings of columns, as well as pages.