Nuclear break-up is a powerful tool to investigate nuclear structure as it is sensitive to the quantum properties of the emitted particles. This reaction mechanism has been used to investigate several aspects of correlations. First, the case of 11Be was studied where the spectroscopic factors for the two configurations where extracted. Secondly, the spectroscopic factor for alpha clusterization in the ground state of 40Ca was measured. Finally the correlation between the two neutrons in the halo of 6He emitted through breakup reactions showed strong contribution for the di-neutron configuration.