Lightning is all the rage these days and, while it's an exciting development, users currently have to have a full node running in order to transact in it. In this article, I'm going to introduce Neutrino, a new protocol for light clients to get the data that they need while preserving privacy and without trusting a central server.
A Little History
In the original white paper written in 2008, Satoshi Nakamoto described something called Simplified Payment Verification (SPV). SPV is how a light node can verify payments without downloading, verifying or storing the entire blockchain. This was supposed to be the basis of light wallets. Unfortunately, the original Bitcoin Core software did not implement Simplified Payment Verification, so light clients did not have access to the data necessary to do SPV in a privacy-preserving way.