Most likely you know that WordPress is bundled with the HTML WYSIWYG editor, TinyMCE. The variety of features, and the ability to be extended though plugins, make it the most used WYSIWYG editor in the world. WordPress doesn't make use of all its features, however. WordPress customizes it and only keeps parts which are really helpful to users, avoiding messing up the user interface. That also means some features, buttons for example, have been hidden from users. You can totally enable the hidden MCE buttons. Typically they are stylesheet, sub, sup buttons. If even the hidden ones still don't satisfy your needs, then you have to create a TinyMCE plugin to do add your own. In this tutorial, I will walk you through the basics of adding your WordPress Editor buttons by creating a TinyMCE plugin.