Ethereum
How does Ethereum work, anyway?
Development
Making Sense of Ethereum’s Layer 2 Scaling Solutions: State Channels, Plasma, and Truebit Febr, 2018
Issues
The Ethereum-blockchain size has exceeded 1TB, and yes, it’s an issue
This isn’t scaling. When your node can’t stay in sync it downgrades to a light client. Now with sharding it can downgrade to a “shard node” . None of this matters. You’re still losing a full-node every time one downgrades. What’s even worse is they are calling all the green dots nodes even though they are only syncing the headers and trusting the red nodes to validate.