title: Can a third-party script set a first-party cookie?
body: <p>I've read a lot of content online about cookies, but nothing addressing this question:  Let's say I have a server at a.com and a web page served by b.com embeds a script in that web page which lives on my server:</p>
  
  <pre><code>&lt;script src='a.com/script.js'&gt;&lt;/script&gt;
  </code></pre>
  
  <p>What is that script allowed to do in terms of setting cookies?  Can it set a cookie with <code>domain=a.com</code>?  I'd assume so since the script is served from that domain.  Can it also set a cookie with <code>domain=b.com</code> since the page is served from that server? </p>
  
  <p>I'm trying to get my head around what "first-party" and "third-party" mean in the context of my script called from another host's web page.</p>