An indent is the space between your margin and your text. Don't confuse the margin and the indent. The indent feature is often used to set a first-line indent for paragraphs.
Clicking the Increase/Decrease Indent buttons is the most convenient way of setting a left or right indent. Each time you click the Increase Indent or Decrease Indent button, your text is moved 0.5 inches by default.
Remember, there is a difference between indents and tabs. If you set a tab, only one line of text is indented. If you click one of the indent buttons or set an indent in the Paragraph dialog box, all of the text you type afterward will be indented.