Starting with some general aspects of higher form symmetries, I will focus on 1-form symmetries in 4d theories. The charged objects under 1-form symmetries are the Wilson and 't Hooft line operators. After discussing general field theoretic implications of 1-form symmetries, the main topic of the talk will be the 1-form symmetries of theories of class S (4d N=2 supersymmetric theories) and their N=1 deformations. The 1-form symmetry will be formulated in terms of the underlying curves (Gaiotto curve and Seiberg Witten curve), and the N=1 generalization thereof. As applications, I will discuss pure Super-Yang Mills and show how the curve encodes the confinement properties of its IR vacua, as well as the confining index in more general settings.