The Takings Clause, a key part of the Fifth Amendment, prohibits the government from taking private property for public use without just compensation. When the government takes private property, it is required to pay just compensation (generally an approximate of the market value of the property) to the property owner for his or her loss.
In this way, the takings clause strikes a balance between the rights of private property owners and the right of the government to take that property for a purpose that benefits the public at large. The takings power of the government, sometimes referred to as the power of eminent domain, may be used for a wide range of valid public uses (for a highway or a park, for example).
www.justicelearning.org, The United States Constitution, what it says, what it means, A Hip Pocket Guide (Oxford University Press)