Guest checkout allows your shoppers to checkout without having to create an account (anonymous checkout). This article discusses the possible values available for the Configuration - Settings - GuestCheckout
Important concepts to understand about guest checkout:
Shoppers who checkout as a guest will not be 'registered' customers. Therefore they will not be able to login with their account later, and they will not be able to view their order history for their guest checkouts.
Shoppers who checkout as a guest can potentially be entered in the database with the same email address as a registered account.
The software does not allow two registered customers with the same email address to be created on the same store. In other words email addresses will be unique among registered customers on a given store. Note that there are exceptions in some circumstances.
The manner of handling Guest Checkout (also known as 'Anonymous Checkout') has changed with AspDotNetStorefront v10.
The storeowner should decide which of four models is being implemented on his store. (In a MultiStore setup, each domain can be operated independently under different Guest Checkout rules.)
The options are:
1) Disabled : Any shopper making a purchase on the store must create a registered account, accessible with a customer created password. On subsequent visits to the store, the password will be required to checkout.
2) AllowUnregisteredCustomers : This is the default setting and most common option. If a shopper is using an email address that is already registered, then a password is required to checkout. However, the owner of an email address that hasn't previously registered can choose whether to create a password (register) or not. Once an account is registered, that email address cannot be used to shop anonymously.
3) AllowRegisteredCustomers : If a shopper checks out using an email address that is already registered, they are given the option to login (orders are added to their account history), or skip the password entry (order anonymously with the order not saved to their account history).
NOTE: At this time, this option is allowing registered emails to be registered again, creating multiple records. This will cause issues with attempts to login to an account with multiple emails. It is recommended not to use this option.
4) PasswordNeverRequestedAtCheckout : A storefront with this setting will never ask for a password during checkout - every order is treated as a guest order. A shopper can register through the 'create account' process, and can be logged in during the checkout, but the All-In-One checkout will not require login from anyone.
NOTE: At this time, this option is allowing registered emails to be registered again on the Create Account page, creating multiple records. This will cause issues with attempts to login to an account with multiple emails. It is recommended that if this option is used, to remove links to the Login/Create Account pages in the site template.
A store owner should give careful consideration to the behavior they choose and can set their preference by navigating to Configuration>Settings and searching for the word 'guest'.