What are the different types of nuclear reactions

What are the different types of nuclear reactions, including fusion, fission, and radioactive decay, and how do they contribute to processes such as energy production in stars, nuclear power generation, and the formation of elements in the universe?Statistical Mechanics: Can you discuss the concept of phase transitions in statistical mechanics, including examples such as the liquid-gas transition and the ferromagnetic-paramagnetic transition, and how they are described in terms of order parameters and critical phenomena?