Sterol is an organic compound with formula C
₁₇H
₂₈O, whose molecule is derived from that of gonane by replacement of a hydrogen atom in position 3 by a hydroxyl group. It is therefore an alcohol of gonane. More generally, any compounds that contain the gonane structure, additional functional groups, and/or modified ring systems derived from gonane are called steroids. Therefore, sterols are a subgroup of the steroids. They occur naturally in most eukaryotes, including plants, animals, and fungi, and can also be produced by some bacteria (however likely with different functions). The most familiar type of animal sterol is cholesterol, which is vital to cell membrane structure, and functions as a precursor to fat-soluble vitamins and steroid hormones.

Sterol

Names
IUPAC name 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17-hexadecahydro-1H-cyclopenta[a]phenanthren-3-ol
Other names Hexadecahydro-3H-cyclopenta[a]phenanthrene-3-ol
Identifiers
3D model (JSmol)	Interactive image
ChemSpider	1076
KEGG	C00370
PubChem CID	1107
InChI InChI=1S/C17H28O/c18-13-6-9-15-12(10-13)5-8-16-14-3-1-2-11(14)4-7-17(15)16/h11-18H,1-10H2 Key: FPXSXMFOYWRHDX-UHFFFAOYSA-N
SMILES C1CC2CCC3C4CCC(CC4CCC3C2C1)O
Properties
Chemical formula	C17H28O
Molar mass	248.410 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

While technically alcohols, sterols are classified by biochemists as lipids (fats in the broader sense of the term).

The gonane skeleton, with the IUPAC recommended numbering of the carbon atoms