The password itself is not stored in AD in decryptable form. As I understand it what is stored is a hash of the password and the date/time when the password was set. When a user logging on enters the password that value and the date/time when the password was last set are used to re-calculate the stored hash. if this is the same as the stored hash, the assumption is that the user entered a valid password.
Full Definition of CREDENTIAL. 1. : something that gives a title to credit or confidence; also: qualification 3a. 2. plural: testimonials or certified documents showing that a person is entitled to credit or has a right to exercise official power.
What Does Certified Mean? Certification provides independent verification of a certain level of expertise in a particular area. Basically, it means you have completed the steps required to receive a particular designation. But this basic definition comes with a weakness--in some cases, individuals can become certified simply by paying a particular membership fee or by attending the required seminar. Such certifications are meaningless and a waste of time and money. Certifications that mean something are about achieving designations that demonstrate to your employer and/or clients that you are, indeed, an expert in a particular area or areas, and that a reputable, recognizable organization is willing to attest to that.