Social Media Content Rights
<p>Is it possible to have a social media site that leaves the copyright with the creator, but by posting gives the site posting rights? Is this common?</p>

<p>Almost every site does this.  See, for example, the bottom of your screen and read the terms and conditions linked in this text:</p>

<blockquote>
  <p>user contributions licensed under <a href="https://creativecommons.org/licenses/by-sa/3.0/" rel="nofollow noreferrer">cc by-sa 3.0</a> with attribution required</p>
</blockquote>

copyright social-media