PROSPECT, the Precision Reactor Oscillation and Spectrum, is a short-baseline reactor antineutrino experiment. PROSPECT consists of a segmented 4-ton $^6$Li liquid scintillator antineutrino detector that will precisely measure the $^{235}$U fission antineutrino spectrum from the High-Flux Isotope Reactor at Oak Ridge National Laboratory. PROSPECT's high statistics and high resolution measurements of the antineutrino energy spectrum and flux from HFIR's 235U core will be vital to understanding the discrepancies between predicted and measured antineutrino spectra and fluxes observed in previous commercial power reactor neutrino experiments; in addition, PROSPECT will search for the existence of sterile neutrino oscillations at the eV$^2$-scale. PROSPECT's assembly was completed in late 2017 and physics data taking at HFIR began in 2018. This talk explains PROSPECT's physics objectives, describe its experimental design, and cover its installation and initial data-taking.