What does " gif and other graphic data can not be displayed" mean. In the compose window, or in reading mail?

I struggle to find email in my inbox with an included gif. I doubt any of the commercial providers have used them for years. The PNG and Jpg images show up fine in my emails from ebay.

Dear Natt, Thank you very much for your reply. Maybe I was not very in my initial message. In my email , the logo in the message to not appear along with the picture of Matt. For reference see my attached screen shot of the E-mail mesaage that i rec ieved form Mat. Matt's photo is not diplayed,