More and more, we hear talks about hackers entering personal accounts on systems such as Facebook, Twitter, ecademy, Plaxo and many others. There are many reasons why someone's account will be hacked. One of them is the lack of imagination for their password. Plus, some people use the same password for all of their accounts.
So, if you do it right, you will end up with many passwords. On my end, I have one password per account and that means about 400 passwords... That's totally unmanageable in a fairly standard human brain. For this reason, you end up writing down all your passwords