"In the past decade a new, geometric picture has emerged for scattering amplitudes in planar N = 4 super Yang-Mills (SYM) theory. It originated from the observation that the tree-level amplitudes and loop-level integrands of n-point amplitudes for all helicity sectors can be computed using integrals over the Grassmannian space ... In such formulation, amplitudes can be extracted from a Grassmannian integral over a suitable contour which selects a particular sum of residues. Building upon this idea, novel studies revealed the interrelation between the rich combinatorial structure of positive Grassmannians and the physical properties of amplitudes ... From this point of view, the aforementioned residues are associated with positroid cells, which are particular subvarieties inside the positive Grassmannian."