CORS (Cross Origin Resource Sharing) is a specification defined by the World Wide Web Consortium (W3C). It allows the content sourced from a domain, to request resources from a different domain.
For most cross-domain requests, CORS initiates a preflight request. The actual request is sent after the successful completion of the preflight request.
CORS settings in Pega 7 enable you to control and secure the use of the Pega API services embedded in your web or mobile client application.