Synthetic fuels are hydrocarbon fuels that are synthesized from various forms of hydrogen and carbon, usually via multiple steps at high temperature and pressure in the presence of one or more selective catalysts. The carbon is usually provided by CO, CO2 or another (possibly renewable) hydrocarbon feedstock. If the hydrogen is produced by electrolysis using electricity, the resulting synfuel earns the additional designation electrofuel or e-fuel. If the electricity used to power the electrolyzer is fully renewable, e.g., solar, wind, or geothermal, the ultimate designation is renewable e-fuel. Many other monikers apply to specific e-fuels (e.g., power to liquid (PTL, e.g, e-methanol), e-DME, e-ammonia, gas to liquid (GTL), e-gasoline (e-gas), e-diesel, e-SAF (sustainable aviation fuel), etc. The objective of this chapter is to explain simplistically the methods used to produce a synthetic and e-Fuels, and discuss examples with properties nearly identical to existing fossil fuels but with lower carbon signatures. Applications are suggested that justify the greater cost and energy required to produce them.