CORS - What is the motivation behind introducing preflight requests?

Question

Cross-origin resource sharing is a mechanism that allows a web page to make XMLHttpRequests to another domain (from wikipedia).

I\'ve been fiddling with COR

Answer 1

Additionally, for HTTP request methods that can cause side-effects on user data (in particular, for HTTP methods other than GET, or for POST usage with certain MIME types), the specification mandates that browsers "preflight" the request

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