What does this quote mean?

History is written by the victors, so chances are, the other side will written and therefore percieved by the poplace in an unfair, biased, and oftentimes innacuratly. so history books are often unaccurate. so an excellent way to gather information is to read or watch something that is related to, but not written by someone that was a part of the event, location, or person. this quote is pretty much the above in simpler terms.