Abstract: T-linear resistivity is ubiquitous in "strange metals", but has proven challenging for theory. I will describe two electronic scattering mechanisms leading to T-linear resistivity. The first arises when well-defined `cold’ quasiparticles coexists with small pockets of `hot’, classical electrons. A scattering of two cold electrons into one cold and one hot leads to T-linear resistivity. I will argue that this process explains, in detail, the phenomenology of the prototypical strange metal Sr3Ru2O7. Secondly, I will discuss transport in a Hubbard-like model that is solvable at weak hopping (t << U,T). This mechanism is relevant for recent experiments in ultra cold atomic gases and possibly low bandwidth systems such as magic angle graphene.