Choices for electricity generation and consumption are not only affected by technology and socioeconomic factors, but also by laws, policies, and regulations that focus on a range of concerns including oversight of markets, investments, and environmental impacts across the electricity supply chain. Tax codes both exclude (subsidies) and include various types of taxes for different transactions and investments associated with electricity generation. These subsidies and taxes help to incentivize investment in various electricity alternatives. Laws and regulations change over time. Past laws have even explicitly forbid the use of certain fuels for power generation, only to later be overturned, and current tax incentives help promote one or more technologies for power generation.