One of the key results from the Kepler mission is that super-Earths and sub-Neptunes abound in the universe, outnumbering their larger counterparts. Their radii (~1–4 Rearth) and masses (~2–20 Mearth) are consistent with the bulk solid-to-gas mass ratio of 100:1. Basic astrophysical considerations of gas dynamical friction, gravitational scattering, collisional mergers, and gas accretion by cooling inform us that these planets likely emerged in situ, in the late stages of disk evolution. The orbital architecture of the planets closest to the star is shaped by the magnetospheric truncation of the disk at stellar co-rotation, and the tidal interaction between the star and the planet. We will show how the theory of star-disk-planet interaction can describe the observed planet occurrence rate as it varies across orbital periods, planet radii, and stellar metallicities.