Because some people in #aion still don’t seem to understand:
If you want to share something that you didn’t make, either include credit or don’t post it.
If it’s on tumblr, reblog it. The reblog system makes it so easy to share things, the only reason that you’d go through the extra steps of saving and re-uploading everything into a new post is to erase the creator’s name and replace it with yours.
If you found it off-tumblr, the best thing to do is first contact the creator about wanting to share it. If they say no, don’t repost it. Post a link to their page containing it.
Sometimes getting in contact isn’t possible, but in either case, the location you found it should be included in your post. (The same post, visibly- none of those stupid nonexistent easter-egg credit links hidden around the corner and behind your left ear.) Tumblr has a content source system for this exact reason. Use it.
If no other source is entered there or in the post itself, the content is automatically attributed to you. It’s synonymous with claiming ownership of the content and everyone who sees the post will be under the impression that you created it. This is also how copyrights are claimed when artists/writers/etc first publish their work online. This is why people get upset. When you do this with something that isn’t yours, it’s theft. Plagiarism. It’s not appreciation or respect. This applies when sharing things anywhere: any forum, blog, or website.
Tumblr can and will remove content you post that isn’t yours. If the creator didn’t want their work reposted, even with credit, they can ask for it to be removed.
If reposting happens to you, you can report it here: https://www.tumblr.com/dmca
They’re quick about it, and it does extend to edits. It does not extend to toon remodels or Photoshop actions/presets.