🧱 Layer 1, Layer 2 & Rollups
Sidechains, Bridges & Other Paths
Alternatives to rollups, and the risks of moving assets between chains.
6 min read
Sidechains: related, not secured by
A sidechain is its own independent blockchain, connected to a main chain via a bridge - but running its own consensus and its own validators. That's the crucial difference from a rollup: a sidechain does not inherit the main chain's security, no matter how closely it's associated with it.
Sidechains can be fast and cheap precisely because they aren't constrained by posting proofs back to a Layer 1. The cost is that you're trusting the sidechain's own validator set, separately from whatever chain it's connected to.
State channels and sharding
A state channel lets a small group of participants transact directly with each other off-chain, as many times as they like, and only settle the final outcome on the base layer once. It's fast and cheap for that narrow use case, but only really works for participants known in advance.
Sharding takes a different angle: instead of adding a layer on top, it splits the base layer itself into multiple parallel shards that each handle a portion of the network's data and transactions, then coordinates between them.
Bridges: the connective tissue - and the risk
Moving an asset from one chain to another almost always goes through a bridge: tokens get locked (or burned) on the origin chain, and an equivalent representation is minted on the destination chain. Bridges are what let a single asset feel usable across many chains and Layer 2s.
They're also one of the most attacked parts of the entire ecosystem. A bridge concentrates a large pool of locked assets behind whatever validates the lock-and-mint process - smart-contract bugs or a compromised validator set there can be catastrophic, and unlike a rollup, a bridge to a separate chain doesn't get L1-level security for free.
Before bridging meaningful value, check who or what actually secures the bridge - a multisig, a validator set, or light-client verification each carry very different risk.
Check your understanding
3 questions from this lesson, with the correct answer already marked.
1. What's the key difference between a sidechain and a rollup?
- Sidechains are always slower
- A sidechain runs its own independent consensus and does not inherit the main chain's security
- Rollups don't use bridges
- There is no meaningful difference
A sidechain secures itself with its own validators; a rollup instead inherits security from the Layer 1 it settles to.
2. A state channel is best suited for…
- Anonymous, one-off trades with strangers
- Repeated transactions between a known, small group of participants
- Replacing Layer 1 consensus entirely
- Storing NFT metadata
State channels work well when participants are known in advance and transact with each other repeatedly, settling only the final result on-chain.
3. Why are bridges considered a high-risk part of the ecosystem?
- They never get used, so bugs go unnoticed
- They concentrate large pools of locked assets behind their own validation logic, without inheriting L1-level security
- They only work with stablecoins
- They are automatically insured against hacks
Bridges hold significant locked value behind whatever secures the lock-and-mint process, making them a frequent target - and that security is separate from any connected chain's own guarantees.