Many people wonder what the point of the indent marker is when you can just simply press the Tab key. Yes, you can do that, but you risk causing yourself a lot of work later if you need to change the indents.
For example, you've been working on a 50-page document and you've used tabs throughout the document to indent the paragraphs. But now your boss tells you that he wants the paragraphs indented at 1 inch instead of half an inch. If you used indent markers to indent the paragraphs, then all you would have to do is select all the paragraphs in your document and move the indent marker over. This one step will move all the paragraphs at one time. But if you used tabs, you're going to have to add an extra tab to each and every paragraph manually.

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