A few months ago I posted about the common myth that you could not use spaces in passwords. And since that myth was in fact untrue, this post follows on to let you understand why that is so important.
While some gibberish password of at least 8 characters containing at least one of each capital letter, number and symbol and is NOT in part or whole the same as one of your last 10 passwords is highly secure. It becomes very difficult to continue to remember these passwords. Here is where the space helps!
A pass-phrase of How high the 2 kites fly! can fulfill all the requirements for many password rules and it is easy to remember. And I will be very difficult to hack!
You can find out more details at this Lifehacker article on how to begin using passphrases to simplify your remembering of passwords.