Salesforce B2C Commerce (previously known as Demandware) is an SaaS e-commerce platform that utilizes a JavaScript-style scripting language called Demandware Scripting, a templating language called ISML.
In June of 2016, Salesforce acquired Demandware, and renamed the platform to "Salesforce Commerce Cloud". It is also called Salesforce B2C Commerce Cloud.
Here is a link to documentation for the API and usage of this platform.
There are 3 architectures of this framework:
Pipelines (Outdated)
SGJC (Site Genesis JS Controllers)
SFRA (Storefront Reference Architecture)
SFRA is the latest among the above.