Pictures on Wikipedia are almost universally free to use, but sometimes under stipulation. It is generally (but not always) safe to link to Wikipedia pictures -from the standpoint of their stability. Meaning that there is a good chance that a given picture will hang around under its current url and not be replaced or abandoned due to “link rot” (as happens frequently with other Internet locations).
https://upload.wikimedia.org/wikipedia/ ... _Horse.jpg
https://upload.wikimedia.org/wikipedia/ ... G_5539.JPG

The pictures above are hosted at Wikipedia. Only the links to these pictures were posted here – the pictures themselves reside at Wikipedia – not Homedistiller.com. The first two pictures are too large to work within HD's IMG tag limitations(1000 x 1000), but the third one will and thats why we can see it. When a person wants to put his own or copyright-free pictures up at Homedistiller, he has to resize them first (to 800 x 800 or less). The first picture linked above is licensed as copyright free or “public domain” because of its age. The other two pictures are licensed under the Creative Commons Attribution-Share Alike license.
The majority of pictures on the Internet should be considered or treated as copyrighted by default. Not to do so would be to invite trouble. Private websites might object to someone directly linking to their pictures too, as I just did with Wikipedia. Many good, reusable public domain pictures though, can be found sometimes with a little work.
“Google images” is sometimes a very useful tool. If you can't host or link to the pictures themselves you can sometimes point to an image search. For example if you search Google images for the words “cast iron furpy” you get this. But if you enter only the word “furpy” you get a lot of beer can pictures.