The disk(s) of the Milky Way

We present a review of formation of the Milky Way's disk(s). We discuss the most recent disk formation and evolution scenarios that can be probed by the orbital eccentricities of stellar populations. These scenarios are included in two different frames, namely violent origin and secular evolution. They are also arranged in four main models: (i) accretion and disruption of satellites, (ii) disk heating by a minor merger, (iii) in situ formation during/after a gas-rich merger, and (iv) stellar migration (radial and vertical). The majority of the models have been developed according to the Lambda Cold Dark Matter (ΛCDM) cosmogony and are based on advanced numerical simulations. They aim to explain the observational data- chemical (e.g., abundances gradients and the [α/Fe] ratio) and kinematic/dynamical (e.g., rotational velocities and velocity dispersions). Models reproduce only some aspects of the Galaxy disk system because all of them are limited by numerous preliminary assumptions, inevitable numerical ar...