Avalanche® is a network composed of multiple blockchains. Each blockchain is an instance of a Virtual Machine (VM), much like an object in an object-oriented language is an instance of a class. That is, the VM defines the behavior of the blockchain.
This chain implements the Ethereum Virtual Machine and supports Solidity smart contracts as well as most other Ethereum client functionality.
The Subnet EVM runs in a separate process from the main AvalancheGo process and communicates with it over a local gRPC connection.
To learn more about Subnets please read the following article.