add_shortcode()

add_shortcode() — Adds a new shortcode. Care should be taken through prefixing or other means to ensure that the shortcode tag being added is unique and will not conflict with other, already-added shortcode tags. In the event of a duplicated tag, the tag loaded last will take precedence.

Inputs: $tag (string): Shortcode tag to be searched in post content. $callback (callable): The callback function to run when the shortcode is found. Every shortcode callback is passed three parameters by default, including an array of attributes ($atts), the shortcode content or null if not set ($content), and finally the shortcode tag itself ($shortcode_tag), in that order.