Passwords can be easily guessed if they are not secure, or passed on to somebody who is not supposed to know it by an insider.
However, the same flaws in password security that existed in ancient times still exist today. Used liberally by the Romans, and then used even more liberally during World War I and II, it was perhaps inevitable that this security mechanism would be adopted from the earliest form of computing.
Passwords have been used as a method of security since ancient times, when sentries would challenge those wishing to enter a restricted area to verbalize a particular word or phrase.
