Galaxies accrete gas in two main modes: cold and hot. Cold mode gas, which is less than 10^5 K, dominates in low-mass galaxies, while hot mode gas, which is heated to virial temperatures (~10^6 K), dominates in high-mass systems. Cold gas is often accreted along filaments, allowing efficient gas capture from distant regions, while hot gas is more spherical. The transition between cold and hot accretion occurs at a halo mass of ~10^11.4 M☉, consistent with previous studies. This transition is linked to a shift in galaxy properties observed by Kauffmann et al. (2003). The cold mode dominates at high redshift and in low-density environments, while the hot mode dominates in group and cluster environments at low redshift. The cosmic star formation rate (SFR) tracks gas accretion history, with a decline at low redshift due to reduced cold and hot accretion. Cold accretion decreases as infall rates drop, while hot accretion declines due to longer cooling times. If hot accretion were suppressed by conduction or AGN feedback, it could resolve conflicts with elliptical colors and galaxy luminosity function cutoffs. The cold and hot accretion modes are crucial for understanding galaxy formation and evolution, with cold mode playing a larger role in simulations than in standard semi-analytic models. The results highlight the importance of cold and hot accretion in shaping galaxy properties and star formation rates.Galaxies accrete gas in two main modes: cold and hot. Cold mode gas, which is less than 10^5 K, dominates in low-mass galaxies, while hot mode gas, which is heated to virial temperatures (~10^6 K), dominates in high-mass systems. Cold gas is often accreted along filaments, allowing efficient gas capture from distant regions, while hot gas is more spherical. The transition between cold and hot accretion occurs at a halo mass of ~10^11.4 M☉, consistent with previous studies. This transition is linked to a shift in galaxy properties observed by Kauffmann et al. (2003). The cold mode dominates at high redshift and in low-density environments, while the hot mode dominates in group and cluster environments at low redshift. The cosmic star formation rate (SFR) tracks gas accretion history, with a decline at low redshift due to reduced cold and hot accretion. Cold accretion decreases as infall rates drop, while hot accretion declines due to longer cooling times. If hot accretion were suppressed by conduction or AGN feedback, it could resolve conflicts with elliptical colors and galaxy luminosity function cutoffs. The cold and hot accretion modes are crucial for understanding galaxy formation and evolution, with cold mode playing a larger role in simulations than in standard semi-analytic models. The results highlight the importance of cold and hot accretion in shaping galaxy properties and star formation rates.