What is "cors"

Cross-Origin Resource Sharing or simply CORS is a specification that enables access beyond the domain from which your page or Application was loaded.

The staff of enable-Cors.org created a website to provide the necessary data to developers to improve their applications.

Why CORS is so important?

Javascript and programming for the WEB has grown by leaps and bounds over the years and the policy of restricting access to the same domain of origin still remains for security reasons. Preventing Javascript from ordering and requesting beyond the boundaries of the current domain provides additional security. The need however is there in our applications so were generated several solution proposals to make requests between domains (JSONP for example).

However these solutions are capengas and CORS came up to resolve this issue.

The CORS introduces a standard mechanism that can be used by all browsers for implementing secure requests across different domains.

The specification CORS sets a set of headers that allow the browser and server to communicate to determine which requests are (and which are not) allowed or secure. The objective of CORS is to continue in the spirit of the open WEB, allowing access to Apis for all users.

It is worth accessing the site enable-Cors.org (in English) for more details.

Another source of research is the questions and answers catalogued in this tag Cors