Single line spacing is a formatting option that refers to the amount of space between lines of text in a document. It means that there is only one line of space between each line of text, making the text more compact and allowing more content to fit on a page. In Microsoft Word, for example, you can single-space your entire document or just part of it by selecting the paragraphs you want to change and going to Home > Line and Paragraph Spacing > 1.0. Single spacing is one of the four types of line spacing available in Word, along with 1.5 times spacing, double spacing, and custom spacing.