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Passwords are the fundamental key to security. They vary in length and complexity. It is good to keep them complex and long but memorable. Choose passwords that mean something to you. Also add numbers with the letters.

Follow up:

What happens is that a hacker will write a program that tests random or incrementing passwords: a1, a2, a3... bob111, bob112,...

The process is very fast but a more complex password that contains letters and numbers will take a long time for a hacker or program to figure out. Many computer systems now will only allow a few attempts at entering the right password anyways.

How do I test my password's strength?

To test the strength of a password visit:
Microsoft’s Password Checker Online Utility.

What makes up a strong password?

A strong password should appear to be a random string of characters to an attacker. It should be 14 characters or longer, (eight characters or longer at a minimum). It should include a combination of uppercase and lowercase letters, numbers, and symbols.

About Password Checker

Password Checker does not collect, store, or transmit information beyond the computer that you use to access Password Checker. The image works on your computer desktop until you navigate away from the page.

The security of the passwords entered into Password Checker is similar to the security of the password you enter when you log into Windows. The password is checked and validated on your computer, but is not sent over the Internet.