We will be releasing separate ELI5 threads on @SkaleNetwork, @omgnetworkhq, @optimismPBC and @zksync in the coming days.
L2 scaling techniques move txs off-chain and bundle them into proofs that are submitted back to the main chain (external scaling).
L1 scaling techniques try to improve the throughput of the main chain through sharding (internal scaling).
1. State channels
2. Sidechains
State channels assume a fixed set of participants where everyone acts as a validator, whereas sidechains have a separate validator set and allow anyone to use the network.
In state channels, state changes are made by a fixed set of live participants.
Any update to the channel must be digitally signed by all channel participants.
They are either:
1. Custodial - assets are moved to a parallel chain with its own consensus mechanism & security.
2. Non-custodial - assets are held & state is secured by smart contracts on Ethereum (= can survive an attack of the sidechain).
Rollups are non-custodial sidechains that solve Plasma's data availability problem.
Rollup blocks include enough data for anyone to reconstruct & challenge their state.
In Plasma, only a subset of validators can challenge blocks sent to the main chain.
1. Optimistic rollups - ORs depend on a dispute game run by active validators.
2. ZkRollups - ZKRs rely on cryptographic zero-knowledge (ZK) proofs, which are instantly validated by a smart contract.
docs.google.com/spreadsheets/d…