Introduction to Bundles

Searchers use Flashbots or Providers like SecureRpc to submit bundles to miners for inclusion in blocks. Bundles are one or more transactions that are grouped together and executed in the order they are provided. In addition to the searcher's transaction(s) a bundle can also potentially contain other users' pending transactions from the mempool, and bundles can target specific blocks for inclusion as well. Here's an example:

const blockNumber = await provider.getBlockNumber()
const minTimestamp = (await provider.getBlock(blockNumber)).timestamp
const maxTimestamp = minTimestamp + 120
const signedBundle = flashbotsProvider.signBundle(
    [
      {
        signedTransaction: SIGNED_ORACLE_UPDATE_FROM_PENDING_POOL // serialized signed transaction hex
      },
      {
        signer: wallet, // ethers signer
        transaction: transaction // ethers populated transaction object
      }
    ])
const bundleReceipt = await flashbotsProvider.sendRawBundle(
    signedBundle, // bundle we signed above
    targetBlockNumber, // block number at which this bundle is valid
    {
      minTimestamp, // optional minimum timestamp at which this bundle is valid (inclusive)
      maxTimestamp, // optional maximum timestamp at which this bundle is valid (inclusive)
      revertingTxHashes: [tx1, tx2] // optional list of transaction hashes allowed to revert. Without specifying here, any revert invalidates the entire bundle.
    }
  )
)

Referenes

Flashbots, Bundles