Certification Aid wants to trigger and email send in Marketing Cloud when a purchase is...

To trigger an email send in Marketing Cloud when a purchase is made on a website, you can use either the REST API or the SOAP API. Both APIs provide methods to send triggered emails.

REST API: The REST API can be used to trigger emails by making a call to the /messaging/v1/messageDefinitionSends/{key}/send endpoint.

SOAP API: The SOAP API can also be used to trigger sends by utilizing the TriggeredSend object.