||This article needs to be wikified. (December 2011)|
A password is a way of authentication. It can be used as a means to identify a person. Since the password is the only way to identify a person, it has to be kept secret. Passwords can be static, and rarely change, or they can be dynamic. Dynamic passwords change as a function of time. A so called one-time pad is a pasword that can only be used once.
Passwords were first used in the military, to tell apart friend and foe, e.g. in darkness.
Today, passwords are made of characters, letters and numbers. Sometimes a password will require a minimum number of characters. Usually this is somewhere from 6 to 8 characters. Some websites do not allow you to use symbols, only letters and numbers. Sites advise that you use a combination of letters and numbers to increase the "strength" of your password. Sites also advise you change your password every year or so to prevent hacking. When typed, each letter of a password is shown as * or •.
Every once in a while, a person may be able to guess your password and hack your account. This is a usually uncommon thing to do, considering a password can be anything.