Role of the storage layer / metadata?

[0xblau]

Hello

I would like to better understand the role played by the storage layer.

From your documentation:

A storage layer is needed to store and recall the metadata information of the shares generated so as to be able to recover the private key from the tKeys generated. 

From the repository on Github:

It's used to encrypt nonces which connects keys to other 'keys' allowing the linking of two accounts, without having to interact with any nodes/other participants.

I would like to better understand:

• What share-related metadata is being stored and how it helps you recover private keys
• What happens if the storage layer is not available
• The definition of "accounts" and "keys" in the sentence above

Thanks