One of the first, natural, methods of testing of anything we use is visual testing. Almost any specimen can be visually examined to determine correctness of size, completeness, the parts count, and the accuracy of fabrication.

 

In many cases visual inspection will eliminate the need for more sophisticated nondestructive testing of the specimen; for example, if the specimen fails visual inspection, then testing by other methods is unnecessary. Visual testing may locate portions of the specimen that should be inspected further by other techniques.