Blocky saysSidechains are independent chains with their own security, bridged to a main chain.
A sidechain (Polygon PoS, Gnosis Chain) runs its own consensus and validators — it does not inherit L1 security like a rollup does. It connects via a bridge for asset movement. Sidechains are fast and cheap, suiting high-volume apps, but you trust their (often smaller) validator set. The key distinction from L2s: a sidechain's security is its own, not the main chain's.
Power-ups you unlock
Own consensus and validators (own security)
Does NOT inherit L1 security
Connected via a bridge
Fast/cheap; trust its validator set
Double-Spend Dan attacks — common mistakes
Calling every scaling chain an "L2"
Assuming sidechain security equals the main chain
Ignoring the bridge as the weak link
Boss battleExplain the core security difference between a rollup and a sidechain.
Example code
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<body style="background:#06040d;color:#e6e0ff;font-family:monospace;padding:20px"><pre>rollup: security borrowed from L1
sidechain: its OWN validators/security, bridged
→ different trust model</pre></body></html>