WP Include File utilizes the WordPress Shortcode to include the contents and output from PHP code located in an external file within the post content.
WP Include File is needed because any PHP code you type within the tinyMCE will not be rendered when the post content is displayed. Hence instead of having to create templates for each specific task/post, you can just create localized specific files and just include them in the post content using WP Include File.
Furthermore it becomes handy when applying specific styles to certain posts that are not required by the rest of the site. Just enclose the style definitions in the style tags, save it in a file and include it in the specific post using WP Include File. Hence you save on bandwidth and load times by not loading unnecessary style definitions where they are not needed.
WP Include File can be invoked using the Shortcode
[include]. The Shortcode accepts four attributes:
variables. It will include the contents of the specified file at the location the Shortcode is placed within the post content. For a full explanation of the implementation read the Help page under the WP Include File Options once the plugin is activated or visit WP Include File's Home