Alcohols, represented by the general formula C_nH_2n+1OH, are organic compounds with a hydroxy group attached to an sp³-hybridized carbon of an aliphatic system.

They exhibit a bent geometry around the oxygen atom, where the sp³ hybrid orbital of oxygen overlaps with the sp³ hybrid orbital of carbon, forming a sigma bond. The carbon–oxygen–hydrogen bond angle approximates the tetrahedral value of 109.5°.

Alcohols are classified as primary, secondary, or tertiary depending on the number of carbon atoms attached to the carbon bearing the –OH group.

The common names for alcohols add 'alcohol' to the name of the alkyl group attached to the hydroxy group.

The IUPAC names are derived from the name of the parent chain by replacing the final '–e' of the suffix with '–ol'. The locant may be before either the parent name or the suffix.

When identifying and numbering the parent chain, the hydroxy group takes precedence, followed by pi bonds, chain length, and lower-priority substituents.

Cyclic alcohols add the prefix 'cyclo' to the parent chain's name. The carbon bearing the –OH group is numbered as one.

When naming polyols, the final '–e' of the parent chain is retained, and multiplier prefixes, like 'di' and 'tri' are added to the suffix '–ol'. The locants of the hydroxy groups are listed together.

Phenols are compounds in which a hydroxy group is attached to an sp²-hybridized carbon of an aromatic ring.

They are named after the parent compound phenol, the simplest hydroxy derivative of benzene. The carbon atom bearing the –OH group is numbered as one.

As with alcohols, polyhydroxy phenols expand the suffix with multiplier prefixes, such as 'diol' or 'triol', and group the relevant locants.

Being aromatic, substituted phenols may use the terms ortho, meta, and para to denote the position of a lower-priority substituent relative to the hydroxy group.