Does exactly what it’s supposed to do

This plugin does exactly what it’s supposed to do. Any key term you add to the glossary automatically appears as a link to the glossary entry. The linked text from the main text stands out clearly as different from other ordinary links.
“Add new” lets you add a new page for each glossary entry.
Confusingly “Add New Glossary Term” adds a category not a term. This is very useful though, once you have worked that out.