Visual vs. Text
You will notice that the text entry box you type your page or post into has two tabs at the upper left. “Visual” is a WYSIWYG editor, that allows you to see most text formatting, images, links, bullets and other features, almost as they will appear in your published page or post. The editing buttons at the top of the text box should be familiar from other word processing programs.
If you don’t see two rows of buttons (you blog’s buttons may look different from the ones shown), you need to use the Toolbar toggle (third from the end on the top row of the above image.) The Toolbar Toggle will switch between one and two rows of writing tools.
Text mode allows you to enter code into WordPress. You need to use it in some cases where the WYSIWYG editor doesn’t correctly interpret code. Examples of when you need to use Text mode are discussed on the Formatting page of this blog.
The Text editing toolbar looks like this:
If you want to try some HTML feature that you can’t figure out how to achieve in the visual editor, it’s worthwhile trying to see if it will work in Text mode.