By default, WordPress’ WYSIWYG editor, TinyMCE, will strip out of your Article and Page HTML code any elements that are not defined as “valid elements”; this can be extremely annoying (especially if you want to include iframes). This plugin will allow you to extend what TinyMCE defines as “valid elements”. By doing so, TinyMCE will no longer remove, delete, or strip-out the additional elements and attributes that you specify. ** NOTE: Make sure after you add elements or attributes you do a hard refresh (ctrl + F5) of your browser on a _TinyMCE screen *(editing or creating a page/post)* so that the TinyMCE cache will be refreshed! You will not see your changes until you do this!