The local government or county can basically seize tax delinquent properties of whose owners did not pay their taxes. Then, the county sells it at a public auction to any interested investor. The winning bidders get the tax deed to the property, giving them right of ownership.
Lots of wise investors readily take advantage of tax deed auctions. Since, it allows them to buy properties at prices well below in today’s market value. Some of them also use this as a way of flipping properties for more profits.