> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chift.eu/llms.txt
> Use this file to discover all available pages before exploring further.

# Invoices

### Definition

An invoice is a document that records a commercial transaction between a seller and a buyer. It states what was sold, the quantities, the prices, the applicable taxes, and the total amount due.

### Purpose

Invoices drive the billing and collection cycle. They serve as the legal record of a sale or purchase.

### Relationships

* Each invoice belongs to a contact (customer or supplier).
* Each invoice line references a product and a tax rate.

### Endpoints

| Method | Endpoint                                                                          | Description                     |
| ------ | --------------------------------------------------------------------------------- | ------------------------------- |
| GET    | [Retrieve all invoices](/api-reference/endpoints/invoicing/retrieve-all-invoices) | Returns a list of all invoices. |
| POST   | [Create an invoice](/api-reference/endpoints/invoicing/create-an-invoice)         | Creates a new invoice.          |
| GET    | [Retrieve an invoice](/api-reference/endpoints/invoicing/retrieve-an-invoice)     | Returns a single invoice by ID. |
| PATCH  | [Update an invoice](/api-reference/endpoints/invoicing/update-an-invoice)         | Updates an existing invoice.    |