Pythnet is an application-specific blockchain operated by Pyth's data providers. This blockchain is a computation substrate to securely combine the data provider's prices into a single aggregate price for each Pyth price feed. Pythnet forms the core of Pyth's off-chain price feeds that serve all blockchains.
Pythnet is powered by Solana technology: it is based on the same validator software, but is a Pyth specific chain that is independent of Solana's mainnet. The Pyth Data Association enables each data provider to operate one validator by delegating them the necessary stake. Once governance is live, it will take over management of validators from the Pyth Data Association.
The Pythnet codebase is a fork of Solana's mainnet codebase. The most recent version of the codebase can be found at
branch pyth-v1.14.17 which includes Pythnet specific changes on top of Solana's mainnet codebase at v1.14.17
(versioned with one more digit at 1.14.17X).