Is your password on this list? If it is, you should probably change it immediately. Even if it's for your favorite online pizza ordering websites because Internet hackers like pizza, too, I'm sure. 

If you're planning on doing some online holiday shopping, a lot of retailers ask you to open an account, so when you come back, they already have your name, address, credit card number, etc. to make shopping later that much easier. When you open that account, they usually need an email address or user names and password.

Most companies ask you to pick a password that's easy for you to remember, but difficult for someone else to guess. Experts say that passwords should contain a combination of upper and lower case letters and even a number or two right in the middle. For example "mIxedUpjenN1fer" is very easy for me to remember, but probably difficult for someone else to guess.

A company called SplashData ran a study of millions of stolen passwords that were posted online by hackers. The ten most common passwords include: 12345678, 1234567, 123456, abc123, password, qwerty, and monkey. Other popular passwords are iloveyou, football and superman.

One other common mistake we make is having the same user name and password combination for multiple websites. If the user name and password is correctly guessed for your account on an online pizza order form, a hacker may correctly guess the user name and password for your bank account, email and Facebook. If you have trouble remembering all of the user names and passwords for all of those websites, there's an app for that.