What is the primary characteristic of non-destructive testing?

The primary characteristic of non-destructive testing is that it does not alter the material being tested. This means that the integrity and usability of the material remain intact after the testing process. Non-destructive testing methods are specifically designed to evaluate the properties and integrity of a material, component, or assembly without causing any damage. This characteristic is significant in fields like engineering and manufacturing, where maintaining the functionality of components after testing is crucial.

In contrast, options suggesting that non-destructive testing requires specialized equipment reflect a common reality; however, the essence of non-destructive testing lies in the preservation of the test subject. The notion that non-destructive testing could damage the subject is contradictory to its definition, as the main goal is to examine materials while leaving them unchanged. Additionally, comparing non-destructive testing to destructive testing in terms of reliability is irrelevant in this context because the two serve different purposes and are applicable in different scenarios, rather than one being inherently less reliable than the other.