Are we talking about Facebook, blogs, Twitter, Instagram, something else?
If it's Facebook then this is normal, if I'm understanding your question correctly. Putting in a link will give you a link and any verbiage which FB will grab. For blogs, it's the meta description (if you use WordPress, then install the Yoast plugin and it's easy to do these). For other kinds of shared links, it's usually the first few sentences or so. But it won't provide the comments coming after that which someone added to comment on the post.
If you're asking if an image is not showing up, try pasting the link in but don't hit post and then navigate to another page and discard the post. Then return and try to post again. Sometimes it takes a little jiggering to get FB to pick up an image. And very large images might not be picked up at all.