Circumstellar disks around young stellar objects are the mass reservoirs from which planets are eventually formed. The structures and properties of the disk, especially in the early stages of protostellar evolution, are critical for globally understanding star and planet formation. It was only in 2012 that the first very young protostellar disk was confirmed kinematically. Today with continuum surveys of nearby star forming regions, we have >600 young disks around protostars with measured fluxes (masses) and radii constraints. With new high-resolution continuum and line imaging of small surveys of young disks, we find that most young disks do not show clear substructures whereas 20% of the older protostellar disk population does present prominent substructures. In the last few years, dust continuum polarization with ALMA has opened a new observational window into the properties of disks. Although not tracing the magnetic field, the observations do place firm constraints on the dust properties and open new questions concerning dust alignment in the disk.