Polygon PoS mainnet is a blockchain application platform. Polygon PoS features a generic validation layer separated from varying execution environments like full-blown EVM sidechains and other layer 2 approaches such as zero-knowledge rollups.

Polygon PoS has a three-layer architecture:

• Staking smart contracts on Ethereum
• Heimdall (Proof of Stake layer)
• Bor (Block producer layer)

The Polygon Mumbai Testnet is a test network created by the Polygon team to provide developers with a sandbox environment to test their applications on the Polygon network. It is designed to be a replica of the Polygon mainnet, allowing developers to test and deploy their applications in a real-world-like environment before releasing them to the production network.

The Mumbai Testnet is an Ethereum-compatible test network that uses the Proof of Authority (PoA) consensus mechanism, which is fast and efficient for testing purposes. It also provides a number of developer-friendly tools and services, including a block explorer, RPC endpoints, and a faucet to obtain testnet tokens for testing purposes.