How does Multi-Signature Pay 2 Script Hash (P2SH) enable stronger security? Coinfloor says it will pay out withdrawals using Multi-Signature Pay 2 Script Hash.  What is Multi-Signature Pay 2 Script Hash?  I read What is &quot;Script Hash&quot; address exactly and how does it work? but didn't understand how it enables more secure withdrawals form cold storage.
Multi-signature is a feature to protect against theft.

From securing your wallet


  Bitcoin includes a multi-signature feature that allows a transaction
  to require the signature of more than one private key to be spent. It
  is currently only usable for technical users but a greater
  availability for this feature can be expected in the future.
  Multi-signature can, for example, allow an organization to give access
  to its treasury to its members while only allowing a withdrawal if 3
  of 5 members sign the transaction. It can also allow future online
  wallets to share a multi-signature address with their users, so that a
  thief would need to compromise both your computer and the online
  wallet servers in order to steal your funds.


Traditional Bitcoin addresses are secured with a single private key. P2SH addresses can associated with three private keys. Depositing funds into is the same as depositing funds into a standard Bitcoin address. However, withdrawing funds from the address requires at least 2 of the 3 keys to sign.