A more thorough explanation:

Definition: The experimental-use exception is a provision in patent law that allows an inventor to publicly use their invention for testing and improvement purposes without losing their patent rights, even if the use exceeds the one-year limit set by the public-use statutory bar.

Example: A pharmaceutical company develops a new drug and wants to test its effectiveness in treating a particular disease. The company can use the drug on patients in clinical trials without losing their patent rights, as long as the use is solely for experimental purposes and not for commercial gain.

Explanation: The experimental-use exception allows inventors to test and improve their inventions without fear of losing their patent rights. In the example given, the pharmaceutical company can use their drug in clinical trials to gather data and improve its effectiveness without forfeiting their patent rights. This exception encourages innovation by allowing inventors to refine their inventions before bringing them to market.