Carbon dioxide (CO2) emissions are a major contributor to the climate change equation, and thus strategies need to be developed in order to reduce increases in CO2 levels in the atmosphere. One of the most promising approaches is to convert CO2 into useful products in engineered processes. The photocatalytic reduction of CO2 into hydrocarbon fuels is a promising way to recycle CO2 as a fuel feedstock by taking advantage of the readily available solar energy. This article reviews the basics of CO2 photoreduction mechanisms, limiting steps, possible strategies to enhance photoreduction efficiency, and the state-of-the-art photocatalytic systems for CO2 reduction. In particular, a comparison between different catalytic systems, including biological (plants and algae), inorganics (semiconductors), organics (molecular complexes), and hybrid (enzyme/semiconductors) systems is provided.