Apple releases two-step verification.

2-step verification process 
Apple have rolled out a two-step verification system that is intended to add extra security to Apple ID accounts a.k.a. iTunes/ iCloud accounts.
  
Once enabled & setup, you will need to use a trusted device to receive notification codes that are used in addition to your account password. The code is used when modifying you Apple ID account info or when purchasing from new devices.
 
The Apple FAQ has lots of information to get started.
 
Limitations & considerations.
You may need to change your current Apple ID password if it is currently weak (fix this now if you only use words in any known dictionary). Account changes put a lock on updating the account security settings, so you may need to wait 3 days to enable two-step verification.
You will need to keep a 14 digit 'recovery key' safe, so that you can access the account settings if your trusted devices are unavailable. The recovery key replaces the security questions - so without it you won't be able to reset the password or change any account settings, the FAQ states Apple can't reset the account password on your behalf once two-step verification is enabled. 
 
Extra layers of security will always add extra inconvenience, so this may not be for everybody, however if you have several devices, it may be a good idea to enable the option.
Your account is now protected with the password, the device & the recovery key.
If you lose or forget two of the three items your account will be inaccessible permanently.