Your build artifacts are saved within the
./build directory, along side the compiled deployed contract artifacts in
What exactly are these artifacts?
It saves the ABI, binary of contract and other info related to the contract. Open the contract_name.json in the ./build/contracts you can see all the information about the contract.If you again wont to deploy the contract then you don't have to compile it will get the contract bytecode from the contract_name.json file of the contract.