What are manual (Draft) orders?

Draft orders allow merchants to create orders on behalf of customers. This is useful for Shopify merchants who receive orders through outside channels, such as chat, on the phone, through sales and support tools, or in person.
Manual orders can be created on behalf of a new or existing customer. You can create orders for your customers and send them invoices from the Shopify admin or the Shopify app.
Additionally, you can save an order as a draft, which will generate a URL. This unique URL will redirect the customers to the checkout page where they just have to add the information and submit the payment.
The orders that you create on behalf of your customers are named draft orders. Draft orders are similar to the orders that your customers create for themselves.
The draft order is converted to an order when customers accept payment for it.

Draft orders can contain the following information:

Draft orders are useful when you need to do the following tasks:

Accept payment for an order that you make over the phone, in person, or elsewhere. When you accept payment for your draft order, an order is created for it on the Orders page.
Send invoices to customers to pay with a secure checkout link.
Use custom items to represent additional costs or products that aren't displayed in your inventory.
Manually re-create mistaken orders from any of your active sales channels.
Sell products at a discount or wholesale rates.
Take pre-orders.
Save the orders as a draft and resume working on it later. If you save your order as a draft, then you can update it later from the Drafts page in your Shopify admin.

Note: You can't edit a draft order after you mark it as paid, mark it as pending, or pay for it using a customer's billing information.