The sci.* hierarchy is a major class of newsgroups in Usenet, containing all newsgroups whose name begins with "sci.", organized hierarchically.
sci.* groups discuss various scientific and research issues.
| Newsgroup | Topic |
| sci.astro | astronomy |
| sci.chem | chemistry |
| sci.crypt | cryptography |
| sci.fractals | fractals and chaos theory |
| sci.geo.earthquakes | earthquakes, volcanoes, tsunamis, and other geological and seismic events |
| sci.geo.geology | geology |
| sci.geo.meteorology | meteorology and weather phenomena |
| sci.lang | languages and linguistics |
| sci.logic | logic and mathematical logic |
| sci.math | mathematics from arithmetic to high level calculus |
| sci.optics | optics and light sciences |
| sci.optics.fiber | fiber optics |
| sci.physics | physics |
| sci.physics.electromag | electromagnetic phenomena |
| sci.physics.relativity | Theory of relativity |
| sci.space.policy | General spaceflight and space policy |