An alcohol is a molecule containing a hydroxyl functional group,$-OH$ group.

Alcohols can be classified as primary, secondary or tertiary.

Alcohols containing two hydroxyl groups are called diols. Alcohols containing three hydroxyl groups are called triols.

Hydroxyl groups make alcohols polar and this gives rise to hydrogen bonding.

→ more hydroxyl groups means more hydrogen bonding, making the intermolecular forces stronger overall