Skepticism has a long historical tradition dating back to ancient Greece when Socrates observed: "All I know is that I know nothing." But this position is sterile and unproductive and held by virtually no one. If you are skeptical about everything, you would have to be skeptical of your own skepticism. Like the decaying sub-atomic particle, pure skepticism uncoils and spins off the viewing screen of our intellectual cloud chamber.
Modern skepticism is embodied in the scientific method, which gathers data to formulate and test naturalistic explanations for natural phenomena, and where a claim becomes factual when it is confirmed to such an extent it would be reasonable to offer temporary agreement. But all facts in science are provisional and subject to change, and therefore skepticism is a method leading to provisional conclusions. Some claims, such as water dowsing, ESP, and creationism, have been tested (and failed the tests) often enough that we can provisionally conclude that they are not valid. Other claims, such as hypnosis, the origins of language, and black holes, have been tested but results are inconclusive so we must continue formulating and testing hypotheses and theories until we can reach a provisional conclusion.
The key to science and skepticism is to continuously and vigorously apply the scientific method to help navigate through the treacherous straights between pure Socratic "know nothing" skepticism, and unmitigated "anything goes" credulity. Over three centuries ago the French philosopher and skeptic Rene Descartes, after one of the most thorough skeptical purges in intellectual history, concluded that he knew one thing for certain: Cogito ergo sum-I think therefore I am. But evolution may have designed us in the other direction. Humans evolved to be pattern-seeking, causal-inferring animals, shaped by nature to find meaningful relationships in the world. Those who were best at doing this left behind the most offspring. We are their descendents. In other words, to be human is to think. To paraphrase Descartes: Sum Ergo Cogito-I Am Therefore I Think.