Uranium enrichment is the process of increasing the percentage of the isotope Uranium-235 in uranium ore. Natural uranium contains about 0.7% of Uranium-235, while the rest is mostly Uranium-238. Enrichment is essential for producing fuel for nuclear reactors and for making nuclear weapons. The enrichment process typically involves techniques like gas diffusion or centrifugation. In gas diffusion, uranium hexafluoride gas is passed through barriers, allowing lighter Uranium-235 to pass through more easily. Centrifugation uses rapid spinning to separate isotopes based on their mass. Both methods aim to produce uranium with a higher concentration of Uranium-235.