What is the powerful of using a website module in dolibarr?

I want to know is the website module can use all operation like create a user inside the website, buy the product on the website, and all of that

I have found that you can extend functionality to page in your website module by using the REST API. However, not every dolibarr module has an API class to work out of. You would have create your own API class for any module that you want to use that does not have an API class.

To check if your API functions were created successfully, visit:
http://yourdolibarrurl/api/index.php/explorer

Currently, I am working on a couple of pages in the website module to allow employees/users to place leave requests and to display their current leave balances. The holiday module does not have an API class. I used the dolibarr module builder and created a new module. Then created an API class for it so that the users can make their leave requests from a form that I built with the website module.

I opted for creating a new module with API functionality because custom modules reside in the htdocs/custom directory in which dolibarr git ignores and does not interfere with the dolibarr system for when I upgrade to the newest dolibarr versions as they are released. Furthermore, using the htdocs/custom directory helps me stay organized with where most of my backend custom work is. And documents/website is where my front end work is with a little bit of custom backend work as needed when the htdocs/custom directory doesn’t make sense.