We define facts as “absolute truth” in critical thinking. With facts, there is no debate. You are reading this right now; that's a fact. Facts are facts; they aren't hearsay, opinions, or rumors.
However, when someone says, “Here are the facts,” that doesn't mean what follows is factual. Remember the most recent presidential (or really, any political) debate? Both candidates stood up and said, “Here are the facts,” yet they contradicted each other. Facts can't be contradictory if they are indeed the one and only truth. So the facts the candidates were throwing at us were not really facts. You could even read in the paper the next day how unfactual their facts were.
When you hear something over and over and over again, you might mistakenly think it's a fact. When someone with great credibility says something, you might assume it's a fact. In either instance, it might be a fact—but unless you know the information to be true, it may not be.
Facts are a very important part of your premise. Because they are absolute truth, you can bank on, leverage, and state facts with confidence. It makes a premise strong. You can come to highly reliable conclusions if you base those conclusions on facts alone. Facts are often the basis for deductive reasoning. Although you don't get to use deductive reasoning often, when you do, it results in correct conclusions.
Mathematics is based on facts. Laws and rules are often used as facts. Science creates rules that, until ...