A more thorough explanation:

Infringement (of Utility Patent) refers to the unauthorized use of all the elements of an independent claim of a utility patent. A utility patent is a type of patent that can be applied for in the United States Patent and Trademark Office (USPTO) for a useful process, machine, article of manufacture, or composition of matter.

The most common type of patent infringement is selling a patented product without authorization. For example, if a company sells a product on Amazon without permission from the patent owner, the company may be infringing on the patent.

Before determining whether a use of a utility patent is an infringement, a court will first decide if the patent is valid. Even if the patent was approved by the USPTO, it can still be invalid. If the patent is found to be valid, the court will then determine the scope and meaning of the patent and compare the alleged infringement to the patent itself.

If the court decides that an infringement exists, the patent holder can receive damages from the infringer, including lost profits and attorney fees.

Company A has a utility patent for a new type of phone charger. Company B starts selling a phone charger that has all the same elements as Company A's patented charger without permission. Company B is infringing on Company A's utility patent and may be liable for damages.

This example illustrates how selling a product that has all the same elements as a patented product without permission is an infringement of a utility patent.