A defect is a commercially produced and distributed good unfit for its intended use.  It is any characteristic of a production which hinders its usability for the purpose for which it was designed and manufactured [A].  A defect is also a non-conformance of a product with the specified requirements, or non-fulfillment of user expectation including the safety aspects [C].  Product defect arise most prominently in legal contexts, where the term is applied to anything that renders the product not reasonably safe.  The defect can also be dangerous or harmful for normal use; this could be due to defective design, assembly, or manufacture [B].

In the first figure, the rope has weak strands which allow it to break in half easily.  The second picture is a ladder with a faulty step.  The wood used for the ladder could have been rotten or filled with knots making it easy to snap when enough pressure is placed on it.  The third picture is a broken chain link.  The connection of the loop was not welded like the other links to which it broke apart.