Some of the basic formatting marks
When formatting marks are turned on, you will see spaces, tabs, paragraph marks and other formatting marks on the screen. Some of the basic formatting marks are illustrated below.
Ctrl+Shift+8 can be used to turn formatting marks on and off.
You can also turn formatting marks on and off by clicking the pilcrow symbol ¶ on the Standard toolbar in Word 2003 or on the Home tab in later versions of Word.
Where to find the options for formatting marks:
For an introduction to the formatting marks and for information about how to turn them on and off, view the demo below.
SHOW ME Formatting marks in Microsoft Word (4:00 min)
About display of text boundaries
In addition to the formatting marks, the demo illustrates how the option Text boundaries works. In Word 2003, Word 2007 and Word 2010, you can turn on text boundaries to have dotted lines shown around margins. This is very useful for layout purposes. Unfortunately, Word 2013 and Word 2016 display text boundaries as dotted lines around each paragraph instead which makes the option very little useful in those versions of Word.
Where to find the option for text boundaries:
Visible formatting marks help you keep track of formatting
Many users who are not familiar with formatting marks get confused if they by incident turn on the formatting marks. However, if you need to control the formatting of documents down to the last detail, visible formatting marks are a must.
You will find more details on this subject in the article "What do all those funny marks, like the dots between the words in my document, and the square bullets in the left margin, mean?" found at the Word MVP site.