Every Snippet can have tags and a format (which are custom taxonomies) attached to it. On display, the plugin will search for snippets with the same tag and/or format, and display one of them acccordingly. If multiple snippets are available, one of them will be randomly choosed on every page refresh.
What will happen if I use a non-existing format/label ?
The plugin won’t display anything.
Can I use the shortcode multiple times to show multiple snippets in the same post ?
Can I de-activate a snippet without deleting it?
Snippets are just like WordPress posts. You can set their status to “Draft” if you don’t want them to appear on your blog.