Passwords can be your best friend or your worst enemy. Passwords are what we use to authenticate that you should have access to whatever software, device or website. This is to keep those who should not have access, out. Do not know or have the right username and password? Get out!
Everyone who uses electronic devices knows they have to memorize usernames and passwords, or at least the pin/shape to unlock a device. Why does everything require this? Because we live in a connected world. Due to the abundance of devices and information and the ease to get to them, in order to protect yourself, everything requires passwords.
When creating to passwords and you boil down all of what you hear down to one goldenrule... it should be something longeasy for YOU to remember and hard for others to guess. That... is... it. It does not need to be complicated or confusing, yet this is what society has trained us. The password can be a short phrase and uncomplicated. Also it is important to be careful and minimize the reuse of passwords. If your password is compromised on a website, there is the probablility that attackers can access your other accounts.
This may seem counterintuitive from what you have been told but the whole concept of uppercase, lowercase, numbers, and special characters is honestly pointless. Why? We have 26 letters in the alphabet; 26 characters to choose at this point. Now give the option to use uppercase and lower case: up to 52 characters. Numbers: now up to 62. Finally you add in special charcaters on the keyboard, 32: You are up to 84 characters. OOPS nevermind, half of the special characters are not allowed: we are back to 79. Let's not forget the Spacebar (Yes you can use spaces sometimes.):70. Next we will talk about why this is important.
Hackers use tools to break passwords. Being able to use these tools to randomly guess what your password is is becoming easier as technology progresses. Mathematically, the difference in speed when guessing passwords when the difference in each character position is between 26 and 70 is negligable considering current computers can calculate at LEAST 200 Trillion instructions per second. The only thing that will save you is length. For every additional character you add, exponentially harder and longer it will take to crack the password. XKCD has a terrific web comic explaining this.