A more thorough explanation:

Nonliteral infringement is a legal theory used in patent law to find infringement when the accused product or process falls outside the literal scope of the patent claims. This theory was created to prevent parties from avoiding liability for patent infringement by making trivial changes to the product or process to avoid the literal language of the patent claims.

For example, if a patent claims a device with a specific element, and another company creates a device without that exact element but with an equivalent element that performs the same function in the same way to achieve the same result, it may still be considered infringement under the doctrine of equivalents.

The doctrine of equivalents is not an absolute bar to a patentee who seeks to invoke it to prove infringement on a claim that was voluntarily amended. However, prosecution-history estoppel may limit the scope of the doctrine.

Overall, nonliteral infringement is a way to protect patent holders from infringers who try to make minor changes to avoid liability.