I will discuss line defects in certain supersymmetric quantum field theories. The spectrum of BPS states of these theories can be determined by studying an effective supersymmetric quantum mechanics based on a certain graph, called quiver. These methods can be generalized to study line defects. A line defect can be characterized by the BPS states that can be bound to it, the so called framed BPS states. I will discuss methods to study framed BPS states using cluster algebras and localization techniques.
