No more stale links to other entries because someone changed the slug
Reference tags are similar to shortcodes in that they are short snippets that return dynamic content. For reference tags, the content comes from Craft Elements such as users, entries, categories, etc.
The Craft docs for Reference Tags (opens new window) gives a pretty in-depth explanation of what they are and how to use them.
Doxter adheres to Craft’s parsing rules when processing reference tags and they get parsed before the markdown gets parsed, allowing for some pretty awesome functionality.