Because humans are really bad at coming up with truly random passwords. People often use words or numbers that mean something to them: a pet’s name, their mother's maiden name, their kids’ birthdays, song lyrics, etc The problem with this is that you end up with passwords that are easy to guess.

And remember: it’s not humans who are doing the guessing. It’s computers. An ordinary desktop computer can test over a hundred million passwords per second — and this number climbs to billions of passwords per second if the computer is using GPU-based cracking tools. Password length and complexity are essential.

So don’t risk it. Use a random password generator to create long, truly random passwords that even the strongest computers can’t crack.

Good passwords are long — like really long (think over 16 characters) — and random. That’s it. The problem here is that humans are really bad at remembering long, random passwords. That’s why you need Avast Passwords, a free password manager that can not only generate long, truly random passwords for you, but also remember them all and automatically log you in to your accounts.

Yes! Using the same password across multiple accounts is a huge no-no. If hackers learn the password to one of your accounts, they’ll have your password for all the others, too. So never recycle passwords. Use different, unique passwords for every account. (And no, simply adding an exclamation mark or other character to the end of a password does not make it unique or strong. Hackers can easily crack variations of passwords like this.)

Here are the 10 worst passwords of 2017. Avoid using these passwords at all costs. If you use any of these — or even variations of these — you’re asking to be hacked.

1. 123456
2. Password
3. 12345678
4. qwerty
5. 12345
6. 123456789
7. letmein
8. 1234567
9. football
10. iloveyou

Remember, short passwords are weak passwords. They’re too easily cracked. For the best password security, you need a long, complex password composed of a random string of characters. You should also avoid common words and phrases to prevent a dictionary attack. Only then will you have a strong password.