Salesforce Apex REST API
Salesforce Apex REST enables developers to expose custom Apex classes as RESTful web services. By annotating Apex classes and methods with @RestResource and HTTP method annotations, developers can create custom API endpoints that extend Salesforce functionality.
Documentation
Documentation
https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_rest.htm
GettingStarted
https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_rest_code_sample_intro.htm
APIReference
https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_rest_methods.htm