The mutual coupling amongst the different 1H's makes the 1H-RMN severely complex.
The recording of a 2D H/H COSY, acronym of "bidimensional proton/proton COrrelation SpectroscopY", enables us to figure out how the 1H's are arranged in the molecule as chains of coupled vicinal groups.
You'll understand (and freak out!!!) in a short while...
