In this video tutorial I'll be explaining what the "Access-Control-Allow-Origin" HTTP Response Header is used for, and how to resolve one of the most common errors you'll get when using AJAX or Fetch. Support me on Patreon: https://www.patreon.com/dcode - with enough funding I plan to develop a website of some sort with a new developer experience! For your reference, check this out: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin Follow me on Twitter @dcodeyt! If this video helped you out and you'd like to see more, make sure to leave a like and subscribe to dcode!