All of those words can be used to indicate more information. Besides, you might not be aware of how often you use these words. Furthermore, you will see these three words quite often in informational essays and in many speeches which deal with a constant flux of information. In addition, all of these words have a similar meaning:
Besides: <em>"in addition to; apart from"</em>
Furthermore: <em>"in addition; besides (used to introduce a fresh consideration in an argument)."</em>
