In the Author mode, you can control the amount of displayed markup
using the following dedicated actions from the 
Tags display mode drop-down menu that is available on
the toolbar:
Full Tags
with Attributes- Displays full tag names with attributes for both block level and in-line level elements.
Full
Tags- Displays full tag names without attributes for both block level and in-line level elements.
Block
Tags- Displays full tag names for block level elements and simple tags without names for in-line level elements.
Inline
Tags- Displays full tag names for inline level elements, while block level elements are not displayed.
Partial
Tags- Displays simple tags without names for in-line level elements, while block level elements are not displayed.
No
Tags- No tags are displayed. This is the most compact mode and is as close as possible to a word-processor view.
To set a default mode of the tags mode, go to Author preferences page and configure the Tags display mode options. However, if the document opened in Author mode editor does not have an associated CSS stylesheet, then the Full Tags mode will be used.
Block-level elements are those elements of the source document that are formatted visually as blocks (for example, paragraphs), while the inline level elements are distributed in lines (for example, emphasizing pieces of text within a paragraph, inline images, etc). The graphical format of the elements is controlled from the CSS sources via the display property.