(N/A) hydrogen bond is defined as an attractive force acting between the hydrogen atom attached to an electronegative atom of one molecule and an electronegative atom of a different molecule (or the same molecule).
Due to the difference in electronegativities,the bond pair between hydrogen and the electronegative atom is shifted away from the hydrogen atom. As a result,the hydrogen atom acquires a partial positive charge $(H^{\delta+})$ and the electronegative atom acquires a partial negative charge $(X^{\delta-})$.
$H^{\delta+} - X^{\delta-} \dots\dots H^{\delta+} - X^{\delta-} \dots\dots H^{\delta+} - X^{\delta-}$
The magnitude of $H$-bonding is maximum in the solid state and minimum in the gaseous state.
There are two types of $H$-bonds:
$(i)$ Intermolecular $H$-bond,e.g.,$HF$,$H_2O$.
$(ii)$ Intramolecular $H$-bond,e.g.,$o$-nitrophenol (as shown in the structure).
Hydrogen bonds are stronger than van der Waals forces because hydrogen bonds are considered an extreme form of dipole-dipole interaction.