A Mainnet in cryptocurrency is the main blockchain network of a specific cryptocurrency project. It serves as the primary platform for processing transactions, validating blocks, and facilitating the transfer of the native cryptocurrency.

The Mainnet is the live and operational version of the blockchain, where all real transactions occur. It is distinct from a Testnet, which is a separate network used for testing new features, upgrades, or changes before they are implemented on the Mainnet. Launching a Mainnet is a crucial milestone for a cryptocurrency project, signaling that it is ready for real-world use by the community.

It demonstrates that the technology has been thoroughly tested and is stable enough to handle actual transactions securely and efficiently. The Mainnet is where users can interact with the cryptocurrency, send and receive funds, and participate in the network's activities, such as mining or staking. Overall, the Mainnet is the backbone of a cryptocurrency project, providing the infrastructure for its operations and functionality.