Privacy and anonymity in Ethereum

We have so far discussed the differences between public and private networks, where it is the network itself, and access to it, which is either public or private. We now turn our attention to the data—both transaction and contract data—inside a given network.
The Ethereum main network can be joined by anyone. Furthermore, all transaction and smart contract data is public, meaning all transactions between a to and from address can be seen by everybody using the network. There is no way to hide these transactions, or the addresses transacting, and as such, there's no way for a user on Ethereum to be truly anonymous. If a way were found to link an address with a real-world identity—either at the present time, or at a point in the future—then the identity of the transacting party would be known. This might seem obvious...