What is the issue CORS is trying to solve?

Question

I\'ve been reading up on CORS and how it works, but I\'m finding a lot of things confusing. For example, there are lots of details about things like

Answer 1

There are security and privacy reasons for not allowing requests from anywhere. If you visited my website, you wouldn't want my code to make requests to Facebook, reddit, your bank, eBay, etc. from your browser using your cookies, right? My site would then be able to make posts, read information, place orders, etc. on your behalf. Or on my behalf with your accounts.