style set is present combination of fonts, paragraph line spacing, character spacing,and indentation. style set enable you to quickly change the look of the document without manually reformatting each paragraph

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Style Sets, located on the Design tab in Word 2013, are preset combinations of character, heading, and paragraphstyles. They're available in a visual gallery on the Design tab and are great for formatting (or reformatting) your entire document at once rather than piecemeal.