The properties of the various types of energy sources that are used to produce hydrogen will be the primary emphasis of this chapter. The method that is utilized to generate hydrogen is governed by several factors, such as the effectiveness of the conversion process, the accessibility and cost of feedstocks, environmental issues, and the eventual application that is desired for the hydrogen. Ongoing attempts to improve efficiency and reduce the environmental impact of hydrogen production are being driven by advancements in technology as well as an increased focus on sustainability. Green hydrogen, which is produced through water electrolysis using renewable energy, is frequently considered to be the most ecologically benign kind of hydrogen. Blue hydrogen, which is produced through natural gas reforming with carbon capture, can give an alternate solution to conventional hydrogen production that results in lower emissions. The continued attempts to improve efficiency and reduce the environmental impact of hydrogen production are being driven by advancements in technology as well as an increased focus on sustainability. Natural gas (methane-CH4) for steam methane reforming; water (H2O) for the electrolyzer; coal, biomass, and other organic matters for the gasification and pyrolysis process; sunlight for the photoelectrochemical (PEC) and photobiological processes; and high temperature heat for the thermochemical water splitting process are all examples of the various energy sources that can be utilized in the production of hydrogen through a variety of processes.