A personal identification number (PIN) concealed behind a paper flap on a letter. Fictional example derived from a real photo at <a href="//commons.wikimedia.org/wiki/File:PIN-Brief.jpg" title="File:PIN-Brief.jpg">File:PIN-Brief.jpg</a>.
<a href="//commons.wikimedia.org/wiki/User:McGeddon" class="mw-redirect" title="User:McGeddon">McGeddon</a>
<span class="int-own-work" lang="en">Own work</span> This file was derived from: <a href="//commons.wikimedia.org/wiki/File:PIN-Brief.jpg" title="File:PIN-Brief.jpg">PIN-Brief.jpg</a>: <a href="//commons.wikimedia.org/wiki/File:PIN-Brief.jpg" class="image"><img alt="PIN-Brief.jpg" src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/4e/PIN-Brief.jpg/16px-PIN-Brief.jpg" decoding="async" width="16" height="7" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/4/4e/PIN-Brief.jpg/24px-PIN-Brief.jpg 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/4/4e/PIN-Brief.jpg/32px-PIN-Brief.jpg 2x" data-file-width="897" data-file-height="368"></a><br>