Shortcodes are formatting actions that are defined within open and closing square brackets. You will find some of the advanced editing features such as adding an image or a file download link will show up as a shortcode.
A pair of square brackets in your text may be confused with a shortcode, if this happens enter two square brackets instead, you would type [[brackets]] to get [brackets] – but you are unlikely to need to do this normally
You will find the following shortcodes are not available using the editor icon bar and must be typed in as text:
[clear] – ensures text starts below any pictures that are left or right aligned
[pagelist_ext] – generates a summary of all child pages (title and the first three lines of text); if tehre are no child pages then the whole web site is listed so only add this shortcode after you have linked in teh first child page.