  The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton LS detector
at 700-m underground. An excellent energy resolution and a large fiducial
volume offer exciting opportunities for addressing many important topics in
neutrino and astro-particle physics. With 6 years of data, the neutrino mass
ordering can be determined at 3-4 sigma and three oscillation parameters can be
measured to a precision of 0.6% or better by detecting reactor antineutrinos.
With 10 years of data, DSNB could be observed at 3-sigma; a lower limit of the
proton lifetime of 8.34e33 years (90% C.L.) can be set by searching for
p->nu_bar K^+; detection of solar neutrinos would shed new light on the solar
metallicity problem and examine the vacuum-matter transition region. A
core-collapse supernova at 10 kpc would lead to ~5000 IBD and ~2000 (300)
all-flavor neutrino-proton (electron) scattering events. Geo-neutrinos can be
detected with a rate of ~400 events/year. We also summarize the final design of
the JUNO detector and the key R&D achievements. All 20-inch PMTs have been
tested. The average photon detection efficiency is 28.9% for the 15,000 MCP
PMTs and 28.1% for the 5,000 dynode PMTs, higher than the JUNO requirement of
27%. Together with the >20 m attenuation length of LS, we expect a yield of
1345 p.e. per MeV and an effective energy resolution of 3.02%/\sqrt{E (MeV)}$
in simulations. The underwater electronics is designed to have a loss rate
<0.5% in 6 years. With degassing membranes and a micro-bubble system, the radon
concentration in the 35-kton water pool could be lowered to <10 mBq/m^3.
Acrylic panels of radiopurity <0.5 ppt U/Th are produced. The 20-kton LS will
be purified onsite. Singles in the fiducial volume can be controlled to ~10 Hz.
The JUNO experiment also features a double calorimeter system with 25,600
3-inch PMTs, a LS testing facility OSIRIS, and a near detector TAO.
