Biological hydrogen production is a process in which microorganisms convert organic matter into hydrogen gas. This renewable energy production method is of great interest as an environmentally friendly and sustainable energy source. Biological hydrogen production can be accomplished using different methods. The dark fermentation method is a process in which organic substances are converted into hydrogen gas by microorganisms in anaerobic (oxygen-free) environments. In this method, organic materials are subjected to the fermentation process and hydrogen gas is released. This process also offers a solution for waste management. Photo fermentation is a process in which photosynthetic organisms convert organic materials into hydrogen gas using light energy. The light is absorbed by the photosynthetic pigments and provides the necessary energy for hydrogen gas production. In this method, clean hydrogen gas can be produced using solar energy. Biological hydrogen production methods have several advantages. These include the use of renewable resources, low greenhouse gas emissions, waste management and low energy consumption. However, there are also some disadvantages depending on the methods, for example limited light access or the difficulty of obtaining the purity of hydrogen gas. Biological hydrogen production is a promising method to meet clean and sustainable energy needs. Continuous research and development studies continue to increase the efficiency of these methods and eliminate their disadvantages. In the future, with the more widespread use of biological hydrogen production methods, the diversity of clean energy sources will increase and environmental sustainability will be ensured.