At this point I’m too afraid to ask what’s considered as sidechain, L1, L2, and L0?

I thought polygon is an L2 for the longest time, but a couple of tweets from experts suggested otherwise

It’s somewhat debated. Polygon does make snapshot commitments to Ethereum, but whether this is considered inheritance of L1 security (and thus making it a form of L2) versus a side chain operating independently with interoperability is kind of grey. I lean towards L2, but others may disagree.

BDFL of Quilibrium, Eng @ Farcaster, ex-Coinbase, always opinionated, never hydrated

/quilibrium

🤔 Is there something that you know is strictly(not on the grey) sidechain, L0, L1, L2?

Anything that does not commit snapshots to Ethereum but bidirectionally bridges would be a side chain rather than an L2. BSC would be an example of this.

So anything that do rollups(optimistic rollups, etc) can arguably be considered an L2 (some might be in the grey like Polygon)

So based on that, can I say that zkSync is an L2? Or is zkSync just a tool to make an L2 chain?

zkSync is an L2, definitively, as it requires rolling up to the L1 for finality.