In the past two decades, extragalactic astrophysics has witnessed an era of discovery as we have continued to enhance our knowledge on how galaxies, much like our own, formed and evolved over cosmic time. But there are still many unanswered questions. What are the physical drivers of galaxy formation and evolution? How did galaxies change over cosmic time in terms of, for example, their chemical enrichment (metallicities), stellar masses, and dust content? What are the mechanisms that halted ("quenched") the star formation processes? In this project, we will attempt to address these fundamental questions by using a reliable and spectroscopically-backed sample of Ha, Hb+[OIII], and [OII] emitters from the ~10 deg^2 narrow-band survey of the High-z Emission Line Survey (HiZELS) up to z~5. Our sample benefits from a wealth of multi-wavelength data from UV (GALEX FUV) to far-infrared (Herschel SPIRE 500um), as well as newly-acquired spectroscopy from Keck/DEIMOS and Keck/MOSFIRE. This is the largest sample to date of emission-line galaxies for which we can study their clustering evolution which will be the first emission-line based measurement of the large-scale structure and dark matter distribution of the Universe between z~1-5. With the addition of new Keck/MOSFIRE spectra z~1-5 Ha, Hb+[OIII], and [OII], we can expand our knowledge of the physical conditions of the interstellar medium (ISM; e.g., ionization state, dust extinctions, gas kinematics) and measure the mass-metallicity-SFR relation for the first time at z~1-5. Our results will place tight constraints on the evolution of star-formation activities and ISM physics, as well as prepare the stage for future next-generation telescopes, such as WFIRST and JWST (both NASA missions), with their state-of-the-art near-infrared cameras and spectrometers (which will allow observations of rest-frame optical/UV emission-lines at z > 5). Our emission-line selected galaxies are also ideal in Lyman-continuum escape studies to study the reionization of the Universe. In this proposal, we will work towards answering the following questions: (1) What are the typical dark matter halo masses occupied by galaxies and what inherent trends exist between halo mass and the physical properties of galaxies? (2) How does the environment affect their star-formation processes? (3) How strongly does the physical conditions of the ISM (e.g., metallicity and dust content from our spectroscopy) change over time and how it affects star-formation processes? Answers to these questions will set strong/tight constraints for theoretical studies of galaxy formation and evolution (e.g., N-body/hydrodynamical simulations such as EAGLE and Illustris).