{spacing} is about both horizontal and vertical white space, e.g. space between letters or words, or space between paragraphs.

Examples of spacing commands are \hspace and \vspace, but there are any more.

For adjusting the space between the lines of a document, use .

There's also the setspace package. It provides double spacing and one-half spacing, but also arbitrary spacing which can be restricted to environments. If your question is specifically about this package, use .

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