https://www.techdirt.com/articles/20180718/16541140265/appeals-court-wont-yet-review-awful-district-court-decision-that-says-embedding-could-be-infringement.shtml

Back in February we wrote about an absolutely horrible ruling out of a New York court by Judge Katherine Forrest that argued embedding an infringing tweet could be an act of infringement on its own. As we pointed out, if this ruling holds, it would undermine some of the basis of how the internet itself works. The issue here gets a bit into the weeds of both how the internet and how copyright law works. Embedding something on the internet, at a technical level, is really no different than how linking on the internet works. And it's long been established that if you link to infringing content, that alone should not be considered a separate act of infringement. But is embedding? At a very basic level, this is the difference between the two:

Everyone agrees that the first one is not infringing by itself (the original site hosting it, or the person who uploaded it, may be infringing, but not the person linking to it). Most courts have used the "server test" on this question, saying that if you merely embedded the image, a la what's above, it's not infringing for the person who used the embed code. This makes sense for a fairly important reason: if you use an embed code on your site, you never actually have the image on your site. Even if it appears on the site, that is merely because the end user's browser pulls that image in and displays it -- which is exactly how the web was designed to work, with the ability to pull in content from many different places and show it all together.