rainbow tables
That's probably enough to try to get your head around for now ..

Security; it ain't easy.
password
P@ssword
1234
Password1
username1!


.. there's tons of obvious easy ones
then comes the keystroke pattern ones .. type easy password, then hold shift and type it again.
An infamous example of this is 9i0o(I)O .. looks complicated until you type it.
Once you know it, it can be typed extremely fast! .. but it's not a good password ..
I see this stuff daily.


Make your sound your own!
.. I do not work here, but the benefits are still awesome