Modifying Request Headers

When your browser talks to a website, it sends messages called HTTP requests. These requests carry extra info, like metadata, in something called headers.

Headers tell the server things like what browser you're using (User-Agent), what kind of content you expect (Accept), or even authentication tokens (Authorization).

We learned about declarativeNetRequest for blocking and redirecting. It's powerful because it lets the browser handle rules efficiently, without your extension's JavaScript always running.

Today, we'll use it to modify these request headers, adding, changing, or removing them before a request even leaves your browser!