Normalised number of galaxies in the photometric redshift bins of Euclid, as inferred from the Flagship simulation. The sample is split into 13 equally spaced redshift bins defined by z_mean. The redshift distribution of the galaxies inside the bins is estimated computing the histogram of the redshift defined by z_mc. The vertical lines indicate the mean redshifts of the bins, . We note that this is the fiducial setting from Euclid Collaboration (2021), selected to optimise the constraining power of galaxy clustering and GGL with the Euclid photometric sample.