# What is the most significant force that attracts water molecules to each other?

Hydrogen bonding occurs where hydrogen is bound to a strongly electronegative element, e.g. $O$ or $F$. Both $H F$ and $O {H}_{2}$ have disproportionately high boiling points, and $\text{H-bonding}$ is responsible.
The heteratom polarizes electron density towards itself to give ""^(delta+)H-O^(delta-)-H^(delta+); when these dipoles align this is an extra intermolecular force that results in the high boiling point of water and hydrogen fluoride.