The Heavy Photon Search (HPS) is an experiment proposed for Jefferson Laboratory to search for new heavy vector boson(s), aka "heavy photons" or "dark photons" or "hidden sector photons", in the mass range of $20$ MeV/c$^2$ to $1000$ MeV/c$^2$. Such particles will arise if there are additional U(1) gauge bosons in nature, and they will couple, albeit weakly, to electric charge through kinetic mixing. Many Beyond-the-Standard-Model theories predict the existence of additional U(1)'s, and recent observations of high energy electrons and positrons in the cosmic rays may be the result of primordial dark matter annihilating into heavy photons. HPS searches for electro-produced heavy photons that decay in di-lepton pairs using both invariant mass and separated decay vertex signatures. With good mass resolution, heavy photons will appear as sharp resonances above the QED continuum. For suitable values of mass and coupling, heavy photons will have long lifetimes, resulting in discernible secondary decay vertex. The HPS employs a large acceptance forward magnetic spectrometer with precise momentum measurement and vertexing capability, followed by a highly segmented lead-tungstate crystal electromagnetic calorimeter for fast triggering and electron identification. Tracks position is detected by silicon microstrips while the state-of-the-art data acquisition system based on 250MHz fADCs allows for high ratetriggering to fully exploit CEBAF CW, high intensity, electron beam.