  These are lecture notes for a short course given at the Les Houches Summer
School on ``Integrability in Atomic and Condensed Matter Physics'', in summer
2018. Here, I pedagogically discuss recent advances in the study of the
entanglement spreading during the non-equilibrium dynamics of isolated
integrable quantum systems. I first introduce the idea that the stationary
thermodynamic entropy is the entanglement accumulated during the
non-equilibrium dynamics and then join such an idea with the quasiparticle
picture for the entanglement spreading to provide quantitive predictions for
the time evolution of the entanglement entropy in arbitrary integrable models,
regardless of the interaction strength.
