Commonwealth Fusion Systems has raised $4 billion to build the first commercial fusion power plant, with interest from institutional investors. Their technology involves magnetic confinement fusion, similar to the sun's energy release through fusion of protons. Commonwealth is making progress on its demonstration reactor, SPARC, with plans to achieve net energy gain in 2027. The company aims to apply lessons learned from SPARC to its next-generation reactor, ARC, which will power a commercial plant in Virginia. Several startups are working on fusion technology, but Commonwealth faces limited competition in the field and has secured offtake agreements with ENI and Google for electricity generated by ARC. Scientists and the private sector are working towards achieving meaningful net energy gain in commercial fusion, with challenges including optimizing supply chains and developing efficient tokamak materials.