&quot;If you Tweet with a hashtag on a public account, anyone who does a search for that hashtag may find your Tweet&quot;
<a href="https:&#x2F;&#x2F;support.twitter.com&#x2F;articles&#x2F;49309" rel="nofollow">https:&#x2F;&#x2F;support.twitter.com&#x2F;articles&#x2F;49309</a> - and first result searching for anything like &#x27;Twitter hashtag&#x27;.<p>I think that&#x27;s pretty clearly publishing and explicitly choosing to make your image&#x2F;thought&#x2F;whatever available to whatever you #mention. That does seem like granting permission for the #brand to share the content through social spaces. I&#x27;d expect them to ask permission before using it in &quot;actual&quot; advertisements (billboards, signs, commercials, etc), but anything shy of that seems like fair game.<p>The nearest thing I can think to compare it to (pre-Internet) would be mailing a photo to the company; what would you expect them to do with it?