What is the REST Api and how can I make asp.net work with it?

I asked Paypal how to do various payments, and they sent me the following links:
https://developer.paypal.com/docs/api/#payouts https://developer.paypal.com/docs/integration/direct/payouts-overview/ https://developer.paypal.com/docs/classic/mass-pay/integration-guide/MassPayUsingUI/#id101DF0760EX https://developer.paypal.com/docs/classic/mass-pay/integration-guide/MassPayUsingAPI/
These use the REST API.  Whatever that is. 
Is the ...