DSAuth-protected ERC20 token vault
A vault is useful any time you need to segregate token holdings into several distinct buckets, or when you want to set up a shared account, perhaps owned by a ds-multisig.
A DSMultiVault is able to hold any number of different ERC20 tokens.
A DSVault is bound to a single token. It is useful as a handle on the token
that the system can pass around without also needing to transfer the tokens
themselves, or passing a Multivault/Token pair.
Vaults are protected by ds-auth which means they support sophisticated access control out of the box.
Whoever owns or controls a DSVault can tell it to perform token operations,
such as transferring X amount of token Y to account Z, or even(provided the
vault has the necessary approval) transferring X amount of token Y from account
W to account Z.
Anyone is free to make deposits to a vault by simply transferring tokens directly into it using the a transfer function. The owner of a vault can also ask the vault to perform the transfer.
Vaults are very staightforward to understand and think about, and can be a useful building block in many different kinds of applications.