Pseudoscience is a claim, belief or practice which is falsely presented as scientific, but does not adhere to a valid scientific method, cannot be reliably tested, or otherwise lacks scientific status. Pseudoscience is often characterized by the use of vague, contradictory, exaggerated or unprovable claims, an over-reliance on confirmation rather than rigorous attempts at refutation, a lack of openness to evaluation by other experts, and a general absence of systematic processes to rationally develop theories. A field, practice, or body of knowledge can reasonably be called pseudoscientific when it is presented as consistent with the norms of scientific research, but it demonstrably fails to meet these norms. Science is also distinguishable from revelation, theology, or spirituality in that it offers insight into the physical world obtained by empirical research and testing. Commonly held beliefs in popular science may not meet the criteria of science. “Pop science” may blur the divide between science and pseudoscience among the general public, and may also involve science fiction. Pseudoscientific beliefs are widespread, even among public school science teachers and newspaper reporters. The demarcation problem between science and pseudoscience has ethical political implications, as well as philosophical and scientific issues. Differentiating science from pseudoscience has practical implications in the case of health care, expert testimony, environmental policies, and science education. Distinguishing scientific facts and theories from pseudoscientific beliefs such as those found in astrology, alchemy, medical quackery, and occult beliefs combined with scientific concepts, is part of science education and scientific literacy. The term pseudoscience is often considered inherently pejorative, because it suggests something is being inaccurately or even deceptively portrayed as science. Accordingly, those labeled as practicing or advocating pseudoscience usually dispute the characterization.