PRIMA is a far-infrared observatory concept being developed to address timely and
fundamental astrophysics about our origins. It will observe the build-up of stars,
black holes, and dust in galaxies over cosmic time, and trace the masses and water
contents of protoplanetary disks to probe the growths of solar systems. The majority of
observing time will be devoted to Guest Observer programs, with focused PI programs to
address key science to inform community planning.  PRIMA will have spectral,
hyperspectral imaging, and polarimetric capabilities, enabled now for the first time by
extraordinary progress in kinetic inductance detector (KID) array technology over the
last two decades. The telescope will be cooled to 5 K to take maximum advantage of the
KID sensitivities. For observations of atomic fine-structure lines, molecular lines,
and solid-state emission bands, R = 130 spectral coverage will range from approximately
24 microns to 235 microns, with a high-resolution mode across the entire band that will
have a spectral resolving power of a few thousand at 100 microns. R ~ 10
moderate-resolution (hyperspectral) imaging will range from 25 to 80 microns for
rest-frame, mid- and far-infrared spectral energy distribution measurements to
disambiguate star formation and active galactic nuclei in galaxies. Polarimetric
observations from 80 to 264 microns will bridge between the large-scale polarimetry of
the interstellar medium from cosmic microwave background observatories and protostellar
disk-scale interferometric observations to probe magnetic fields at the critical scales
at which clouds collapse to form stars. An overview of PRIMA's basic design and
capabilities will be presented.