Polygon
Polygon is where Polymarket lives. When you deposit USDC to Polymarket, your USDC sits on Polygon; every trade is a Polygon transaction.
Definition
Polygon is an Ethereum Layer 2 network providing cheap, fast transactions. Polymarket runs on Polygon.
Plain-English explanation
Ethereum mainnet is expensive — a single transaction can cost $5–50 in gas. Polygon processes transactions with similar security guarantees but at pennies per transaction. This makes Polymarket economically viable at retail scale. Polygon uses a Proof-of-Stake consensus, has its own native token (MATIC, rebranded POL), and supports the full Ethereum tooling ecosystem. Wallets like MetaMask work seamlessly on Polygon once you add the network.
Example
You trade 100 contracts for $42 on Polymarket. Gas cost for the trade: ~$0.01 on Polygon. The same trade on Ethereum mainnet would cost $5–20 in gas, making the trade economically nonsensical.