# Invoices

An invoice is the basis and the record of a Tilia transaction.
Tilia supports these invoice types:

- **Standard invoice**: A standard purchase invoice involves collecting funds from the buyer and
transferring them directly to the recipient or seller.
Standard invoices work well in standard payment processing applications.
- **Escrow invoice**: An escrow purchase invoice involves collecting funds from the buyer and
holding them in an escrow account, until an agreed-upon condition is met.
Once escrowed, funds can either be transferred to the seller, or refunded back to the buyer.
Escrow invoices are commonly used with non-fungible tokens (NFTs) and products on a blockchain.
- **Virtual token purchase**: This type of invoice enables a user to purchase tokens
from you for use in other transactions.
Tokens can be spent using both standard invoices or escrow invoices.
- **Virtual token conversion**: This is a special type of invoice that can be used to exchange
a user's convertible tokens to fiat currency.
Refer to [Virtual Tokens](../../core-concepts/virtual-tokens) for more information.
- **Payout**: Payout invoices are used to request that funds be transferred from a user's fiat wallet
to an external account (e.g. PayPal.) Refer to [Payouts](../../core-concepts/payouts) for more information.


Tilia supports these transactions from:

- **User to user**: When the one user pays another user for a good or service.
A user-to-user invoice can include user-to-user line items, user-to-integrator line items,
and line items with recipients that are users and a recipient that's the publisher.
- **User to integrator**: When the user pays you, the publisher, for a good or service


Both **Standard** and **Escrow** invoices support transactions in tokens or in fiat currency.

### See Tilia invoices in action

Our [Tutorials](/tutorials) walk you through the process of creating invoices for many different transaction types.

## Invoice properties

The following diagram shows how the contents of an invoice are organized.

![Invoice elements](/assets/concepts-invoice-contents.d25da5ade62dde77fa4c51cef6aa64608c57eacc697038af58fc8ffd2323cae2.9c1bb791.png)

An **Invoice** contains one or more **Line items**. The Line items of a **User to user** transaction can contain one or more **Recipients**.

### Invoice heading

The Invoice contains information that applies to the entire transaction, such as:

- **The invoice's unique ID.** You can use this ID to retrieve the invoice.
For example:

```bash
GET https://invoicing.tilia-inc.com/v2/invoice/{invoice_id}
```
- **The payer's account ID**
- **A description of the transaction overall**
- **The payment methods** that provide the funds for the transactions.
Payment methods include credit cards, Tilia wallets, and PayPal.
- and other details and metadata about the invoice.


### Line item

Each line item contains information about a single item being exchanged in the transaction. Information, such as:

- **Product identification** such as SKU, product code, purchase price, and other metadata.
- **Recipient information** (user-to-user invoice only)
In a user-to-user transaction, each user to receive payment from the
transaction is described individually.
Line items in a user-to-user invoice can have recipients that are users as well as a recipient that's the publisher.


In a user-to-integrator transaction,
the recipient is the publisher and needs no additional information.

### Recipient

Each user to receive funds from the transaction is listed individually in the Line item. This information includes:

- **Descriptive information** data and metadata that describes the transaction.
- **Amount information** that describes the currency type and amount the recipient is to receive.
- **Funding information** that describes the wallet or payment method
that provides the funds, and the account or wallet to receive the funds.


## Invoice lifecycle

A standard invoice moves through the following states: `open`, `processing`, and `success`.
The following diagram shows the invoice states as an invoice moves through its lifecycle.

![Standard invoice lifecycle](/assets/concepts-invoice-lifecycle.37ecb8c65b89c813789259a5f9a876b8da2207817ed44776eecbae3a08195fbb.9c1bb791.png)

If an invoice can't be processed, it is assigned a state of `failed`.
This could happen, for example, if the user's credit card was declined.

An unprocessed invoice can also be canceled, in which case it is assigned a state of `cancelled`.

After a week, unpaid invoices  sare automatically canceled.

## Webhooks

You can use our webhooks to keep track of an invoice throughout its lifecycle.
For information about using webhooks, visit [Webhooks](/webhooks).