e are in the golden age for the search for high-redshift galaxies, made possible by state of the art instruments including the Hubble, Subaru and Keck Telescopes. Two such classes of galaxies, namely Lyman Alpha Emitters (LAEs) and Lyman break Galaxies (LBGs) have rapidly been gaining popularity as theoretical probes of the epoch of reionization, galaxy evolution and the dust enrichment of early galaxies. In this talk, I will present a broad overview of the semi-analytic and numerical galaxy formation models proposed to explain the observed data sets including the Lyman Alpha and UV luminosity functions, colors, equivalent width distributions and spectral slopes. I will also discuss the results from these models regarding reionization, the physical nature and the assembly of these galaxies, the LAEs-LBGs connection and the relation between these early galaxies and the Local Universe, that will be testable with increasing data sets, and future observatories such as ALMA and the JWST.