Simple definition
A WordPress shortcode is a special tag in square brackets that WordPress processes to insert generated content.
Technical definition
A shortcode is registered by WordPress core, a theme or a plugin and mapped to a callback that produces output when the tag is processed. The resulting content depends on the active code and supplied shortcode attributes.
What is a WordPress shortcode used for?
Embed dynamic elements such as galleries, forms or reusable blocks in supported WordPress content.
Practical example
A page editor adds a shortcode provided by a contact-form plugin, and WordPress renders the form when the page loads.
Common problems
- Plugin or theme conflict
- Incompatible update
- Cache hiding the change