Alcohols are organic compounds containing a hydroxyl group (–OH) attached to a saturated carbon atom. Their general formula is R–OH, where R is an alkyl group.
They are classified as:

• Primary (1°): –OH attached to a carbon with one alkyl group (e.g., CH₃CH₂OH).

• Secondary (2°): –OH attached to a carbon with two alkyl groups (e.g., (CH₃)₂CHOH).

• Tertiary (3°): –OH attached to a carbon with three alkyl groups (e.g., (CH₃)₃COH).

Physical properties:
Alcohols are polar, form hydrogen bonds, have higher boiling points than hydrocarbons, and are soluble in water (especially lower alcohols).