# Transaction Overview

## Transaction Types

A transaction type is specified by the strings in the first column in the table below.

Type | Description
---- | -----------
[payment](#payment) | A `payment` transaction represents a transfer of value from one account to another. Depending on the [path](https://ripple.com/build/paths/) taken, additional exchanges of value may occur atomically to facilitate the payment.
[order](#order) | An `order` transaction creates a limit order. It defines an intent to exchange currencies, and creates an order in the XRP Ledger's order book if not completely fulfilled when placed. Orders can be partially fulfilled.
[orderCancellation](#order-cancellation) | An `orderCancellation` transaction cancels an order in the XRP Ledger's order book.
[trustline](#trustline) | A `trustline` transactions creates or modifies a trust line between two accounts.
[settings](#settings) | A `settings` transaction modifies the settings of an account in the XRP Ledger.
[escrowCreation](#escrow-creation) | An `escrowCreation` transaction creates an escrow on the ledger, which locks XRP until a cryptographic condition is met or it expires. It is like an escrow service where the XRP Ledger acts as the escrow agent.
[escrowCancellation](#escrow-cancellation) | An `escrowCancellation` transaction unlocks the funds in an escrow and sends them back to the creator of the escrow, but it will only work after the escrow expires.
[escrowExecution](#escrow-execution) | An `escrowExecution` transaction unlocks the funds in an escrow and sends them to the destination of the escrow, but it will only work if the cryptographic condition is provided.
[checkCreate](#check-create) | A `checkCreate` transaction creates a check on the ledger, which is a deferred payment that can be cashed by its intended destination.
[checkCancel](#check-cancel) | A `checkCancel` transaction cancels an unredeemed Check, removing it from the ledger without sending any money.
[checkCash](#check-cash) | A `checkCash` transaction redeems a Check to receive up to the amount authorized by the corresponding `checkCreate` transaction. Only the `destination` address of a Check can cash it.
[paymentChannelCreate](#payment-channel-create) | A `paymentChannelCreate` transaction opens a payment channel between two addresses with XRP set aside for asynchronous payments.
[paymentChannelFund](#payment-channel-fund) | A `paymentChannelFund` transaction adds XRP to a payment channel and optionally sets a new expiration for the channel.
[paymentChannelClaim](#payment-channel-claim) | A `paymentChannelClaim` transaction withdraws XRP from a channel and optionally requests to close it.

## Transaction Flow

Executing a transaction with `RippleAPI` requires the following four steps:

1. Prepare - Create an unsigned transaction based on a [specification](#transaction-specifications) and [instructions](#transaction-instructions). There is a method to prepare each type of transaction:
    * [preparePayment](#preparepayment)
    * [prepareTrustline](#preparetrustline)
    * [prepareOrder](#prepareorder)
    * [prepareOrderCancellation](#prepareordercancellation)
    * [prepareSettings](#preparesettings)
    * [prepareEscrowCreation](#prepareescrowcreation)
    * [prepareEscrowCancellation](#prepareescrowcancellation)
    * [prepareEscrowExecution](#prepareescrowexecution)
    * [prepareCheckCreate](#preparecheckcreate)
    * [prepareCheckCancel](#preparecheckcancel)
    * [prepareCheckCash](#preparecheckcash)
2. [Sign](#sign) - Cryptographically sign the transaction locally and save the [transaction ID](#transaction-id). Signing is how the owner of an account authorizes a transaction to take place. For multisignature transactions, the `signedTransaction` fields returned by `sign` must be collected and passed to the [combine](#combine) method.
3. [Submit](#submit) - Submit the transaction to the connected server.
4. Verify - Verify that the transaction got validated by querying with [getTransaction](#gettransaction). This is necessary because transactions may fail even if they were successfully submitted.

## Transaction Fees

Every transaction must destroy a small amount of XRP as a cost to apply the transaction to the ledger. This is also called a *transaction fee*. The transaction cost is designed to increase along with the load on the XRP Ledger, making it very expensive to deliberately or inadvertently overload the peer-to-peer network that powers the XRP Ledger.

You can choose the size of the fee you want to pay or let a default be used. You can get an estimate of the fee required to be included in the next ledger closing with the [getFee](#getfee) method.

For a multi-signed transaction, ripple-lib automatically multiplies the `fee` by (1 + Number of Signatures Provided). For example, if you set `instructions.fee = '0.000020'` and `instructions.signersCount = 2`, the prepared transaction's `Fee` will be 20 drops × (1 + 2 Signatures) = 60 drops. See [Transaction Cost](https://developers.ripple.com/transaction-cost.html).

## Transaction Instructions

Transaction instructions indicate how to execute a transaction, complementary with the [transaction specification](#transaction-specifications).

<%- renderSchema("objects/instructions.json") %>

We recommend that you specify a `maxLedgerVersion` so that you can quickly determine that a failed transaction will never succeed in the future. It is impossible for a transaction to succeed after the XRP Ledger's consensus-validated ledger version exceeds the transaction's `maxLedgerVersion`. If you omit `maxLedgerVersion`, the "prepare\*" method automatically supplies a `maxLedgerVersion` equal to the current ledger plus 3, which it includes in the return value from the "prepare\*" method.

## Transaction ID

```json
"F4AB442A6D4CBB935D66E1DA7309A5FC71C7143ED4049053EC14E3875B0CF9BF"
```

A transaction ID is a 64-bit hexadecimal string that uniquely identifies the transaction. The transaction ID is derived from the transaction instruction and specifications, using a strong hash function.

You can look up a transaction by ID using the [getTransaction](#gettransaction) method.

## Transaction Memos

Every transaction can optionally have an array of memos for user applications. The `memos` field in each [transaction specification](#transaction-specifications) is an array of objects with the following structure:

<%- renderSchema('objects/memos.json') %>