Acoustic emission technology has developed to the state where broad applications to materials testing and evaluation are evident. The unique characteristics of acoustic emission as they bear on applicability to nondestructive testing are emphasized.Among the advantages anticipated for the acoustic emission method, two are especially noteworthy: 1. Moving inspection upstream in the production process so that bad production can be eliminated before large fabrication and assembly costs are accumulated. 2. Economical 100% NDT inspection of finished components or products.