Yellow frog instead of a picture

Can anyone explain me why in some posts there is a box with a message saying "Hotlinking has been disabled for this domain" with the drawing of a yellow frog replacing what apparently was a picture posted by someone?
I apologize in advance for my ignorance about these matters and must assume that "hotlinking" provides some service for picture posting which is now discontinued. However I would like to be better informed. Many thanks.

they don't want hotlinks. because it makes trafic. the links shows only the picture, but not the content of the side(example advertise) . so it makes a lot of cost, without having benifit from it.
i hope you get it, its not easy to explain.

Some imagehosters dont like being linked to a porn forum or adult forum.

w suggest that you dont use that site as you can see what happens when you do use it here. There are plenty of fine picture hosts out there. Imagevenue, pix-nofrag, pictiger etc etc.

better to use a recognised reliable host and ensure your pictures remain for a longer period.

Oh phew! For a second, I thought you were talking about me.

Elmo wrote:

Nah we only talk about you in dark corners and back alleys......

Thank you gnoga and Sir_darkstar for the explanation. It seems that some imagehosters don't like our forum. Therefore, posters that want to show their pics in the forum should not use hotlink. Is this interpretation correct? Concerning Mr Elmo, please note that it is a yellow and not a green frog (I also would like to take this opportunity to thank you very much for your many wonderful posts).