Have you ever shared a link on Facebook and the image wasn’t right? It is because the content lacks the proper Open Graph metadata.
By inspecting your web content, Facebook will try to figure it out what type of content is (video, image, blog post) and what’s the right image to include.
Why is this important? One thing is how you beautifully designed your content on your website, and a very different thing is how it will look like on Facebook.
There is one cool tool to diagnose your content: the Sharing Debugger.
You just put your link, and the tool will tell you how Facebook interprets your content, what image it will show, and what are the OG metadata tags missing.
There is an aesthetic component to why users share your content. Besides they find it relevant and feel the impulse to share it, they do it because they will make them look good.