Public interest law is when lawyers work to help people and communities who don't have a voice or power, but need help. This can include helping people who can't afford a lawyer, like low-income people or immigrants, or helping to make sure companies or organizations are doing the right thing, like protecting the environment or helping with things like housing, health care and education. Public interest lawyers may also help pass laws or challenge laws that don't protect the people who need help. So, it's kind of like when superheroes fight to help people who are in trouble, but without having to wear a cape!