What is a good password?

A Word About Passwords
Passwords are often the last, and sometimes only, line of defense. In this paper I will be
using rather simple passwords (test123,123test and testing). This is only
for simplification of the documentation. Never use passwords like these. Always use good passwords.

"What is a good password?
A good password is:
private: it is used and known by one person only
secret: it does not appear in clear text in any file or program or on a piece of paper
pinned to the terminal
easily remembered: so there is no need to write it down
not guessable by any program in a reasonable time, for instance less than one week.
week."
The best recommendation I can make is this don't use real words. Use the first letters
from a sentence that you'll remember (something from a movie for example), change
some characters to upper case and swap some numbers for letters.
As an example, let's take a quote from The Matrix. “What is real? How do you define
real?” and we'll use the first letter from each word.

redlye
We'll change every odd consonant to uppercase (we'll say y is a consonant).
W34Lod
We'll change the i to a 1 and add a space and a non alpha-numeric character.
W43iD
Now we have a password that is private, secret, easily remembered and not easily
guessable by any program.