A glossary defines special terms and acronyms used in the manual. In 3-ring binders, the glossary is placed at the front of the manual after the introduction.
Including a glossary can help standardize definitions of special terms. A glossary also helps by reducing the need for explanations of special terms used in the manual, although having a glossary does not mean you don’t have to define your terms—you do.
When you’re writing glossary definitions, try to keep them to one or two sentences. A glossary is not the place for a detailed description of major concepts. If you find you need several paragraphs to explain a term, consider including it as a topic in the body of the manual.