Employee Retirement Income Security Act (ERISA) is a federal law that sets rules to protect people who participate in retirement and other employee benefit plans. It makes sure plans are run fairly and responsibly, and that the people managing them act in the best interest of the participants. ERISA requires plans to provide clear information, follow certain standards, and give workers a way to file complaints or claims. While many large employer plans must follow ERISA, Solo 401k plans are generally exempt as long as they only cover the business owner and their spouse, making them simpler to manage.