When someone has been given authority to act for someone else, we commonly refer to the authorized person as a proxy. A proxy is someone who acts as a substitute. In proxy testing, the proxy temporarily “becomes” the person being tested. By voluntarily putting themselves into the position of standing in for someone else, a proxy can be tested as if they were the subject of the testing, allowing their body to be used to benefit the subject. Proxy testing is most useful when you want to help someone who is not present or who is inaccessible for some reason.