> For the complete documentation index, see [llms.txt](https://the-wishlist-documentation.gitbook.io/the-wishlist-documentation-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://the-wishlist-documentation.gitbook.io/the-wishlist-documentation-docs/customer-rest-api/overview.md).

# Overview

The Customer API is used to create and manage information about a retailer’s customers, such as their contact details, and whether they’ve agreed to receive email marketing. The Customer resource doesn’t store any credit card information.

A customer must be created before a wishlist can be created for that customer (we currently don’t support anonymous wishlists, as they offer retailer's little benefit).

There are 4 customer identifiers supported:

**customerID** is TWCs internal unique customer identifier

**customerRef** is typically the main identifier assigned to the customer by the retailer (e.g. Shopify identifier)

**email** is mandatory and must be unique

**alternateCustomerRef** is a secondary customer identifier optionally assigned to the customer by the retailer (e.g. ERP identfier or loyalty number)

The only mandatory field when creating a customer is **email**, although we recommend you also assign the retailers customer identifier (**customerRef**) and ideally firstName, lastName.