This is a long description of this image:
https://github.com/w3c/webpayments-ig/blob/master/latest/charters/images/WebPaymentsBasicPaymentFlow.png

The purpose of the graphic is to illustrate at a high level the
payment flow that will be enabled by the standards from the
Web Payments WG. 

The principle entities involved in the flow defined by these APIs are
the Web application, user agent (typically a browser), and digital
payment instrument.

Here are the steps:

1. The payee sends a payment request via the Web application, which
is hosted in the user agent.

2. The user agent looks for registered digital payment instruments
(via the user's digital wallets). If there are no registered
instruments, the payment fails.

3. The user agent then looks for a match between the digital payment
instruments accepted by the payee and those registered by the
payer. In the absence of a match the payment fails.

4. Otherwise the user is prompted to select a payment instrument and
possibly to confirm payment terms.

5. In some cases, the user's choice of payment instrument may enable
payment to proceed without further interaction by the payer or payee.
In this case (e.g., a push payment instrument), a "payment completion"
signal is returned to the payee via the user agent.

6. In other cases, the user's choice of payment instrument may require
additional payee action for payment to complete, or the payee may
explicitly request that payment be deferred until the payee takes
further action or requires the payer to confirm additional details.

7. In these latter cases, to complete payment, processing happens
either on the payee side (for pull payments) or the payer side (for
push payments), and a final signal is sent to the payee when payment
has completed. This signal may be sent by the payment processor
according to the payment scheme, and may not be part of the protocol
specified by this Working Group.