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# Transactions

## Routing

Ethermint needs to parse and handle transactions routed for both the EVM and for the Cosmos hub. We
attempt to achieve this by mimicking [Geth's](https://github.com/ethereum/go-ethereum) `Transaction`
structure and treat it as a unique Cosmos SDK message type. An Ethereum transaction is a single
[`sdk.Msg`](https://godoc.org/github.com/cosmos/cosmos-sdk/types#Msg) contained in an
[`auth.StdTx`](https://godoc.org/github.com/cosmos/cosmos-sdk/x/auth#StdTx). All relevant Ethereum
transaction information is contained in this message. This includes the signature, gas, payload,
etc.

Being that Ethermint implements the Tendermint ABCI application interface, as transactions are
consumed, they are passed through a series of handlers. Once such handler, the `AnteHandler`, is
responsible for performing preliminary message execution business logic such as fee payment,
signature verification, etc. This is particular to Cosmos SDK routed transactions. Ethereum routed
transactions will bypass this as the EVM handles the same business logic.

Ethereum routed transactions coming from a web3 source are expected to be RLP encoded, however all
internal interaction between Ethermint and Tendermint will utilize one of the supported encoding
formats: Protobuf, Amino or Hybrid of the previous two.

## Transaction formats

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- Cosmos transactions
- Ethereum transaction

## Signatures

Ethermint supports [EIP-155](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md)
signatures. A `Transaction` is expected to have a single signature for Ethereum routed transactions.
However, just as in Cosmos, Ethermint will support multiple signers for non-Ethereum transactions.
Signatures over the `Transaction` type are identical to Ethereum and the signatures will not be
duplicated in the embedding
[`auth.StdTx`](https://godoc.org/github.com/cosmos/cosmos-sdk/x/auth#StdTx).

## Next {hide}

Learn about how [gas](./gas.md) is used on Ethermint {hide}
