What is a provider and what is a signer in Ethers.js?

• Provider: A read-only connection to the Ethereum network. It can query blockchain data like balances, transaction history, and call view functions on smart contracts, but cannot send transactions.

• Signer: An abstraction that can sign transactions and messages. It has access to a private key and can send transactions to the network.

// Provider - read-only
const provider = new ethers.providers.JsonRpcProvider();
const balance = await provider.getBalance(address);

// Signer - can send transactions
const wallet = new ethers.Wallet(privateKey, provider);
const tx = await wallet.sendTransaction({
  to: "0x...",
  value: ethers.utils.parseEther("1.0")
});