Positroid varieties are certain subvarieties of complex Grassmannians playing an important role in the theory of totally nonnegative Grassmannians. The positroid varieties can be defined in Lie theoretic terms and also admit an explicit description in terms of linear algebra, leading to a natural embedding into certain quiver Grassmannians for equioriented cyclic quivers. Varying representations of the quiver, one defines global positroid varieties. We will discuss the properties of the global positroid varieties and their connection to the type A affine Grassmannians. -- This seminar is part of the activities of the Project PRIN 2022S8SSW2 funded by the European Union – Next Generation EU.