1. Is it legal to use thumbnails low-res photos from royalty free images sites without any payment at my site?

2. Is it legal to use the photos in med-res (after clicking the thumbnail photo) from here without any payment at my site?
http://www.punchstock.com/store/main

Thanks

I think you will probably find that it is illegal to use to images in any shape or form.

If you want completely free images try http://www.sxc.hu/index.phtml, the vast majority of images there seem to be totally free.

I think I have heard somewhere that royalty free = free image to use (and not resell) once you buy them. So by your answer maybe this is wrong.

1. So I am little confused, what is the meaning of royalty free images?
2. Is it legal to use these royalty free picture on my site if I buy them?
3. If I don't buy the high res pictures, and use the low-res thumnails on my site how can they know I did not buy it?

istockphoto.com
this site has royalty free pics, but they usually cost $1 an image

If pics are royalty free and not copyrighted, I don't see how you would get in trouble.

I could be wrong though

If you pay for them then that's fine. You can use them on your website. You can't sell them on though. The fact of using a low resolution thumbnail without paying and hoping they wont find out is more of a moral question. Chances are you would get away with it, but would you like it if someone did it to you?

'Royalty Free' means that there are no lasting copyrights on the image, and that you can then re-use it as many times as you wish. It isn't, as some people often think, a reflection of cost.

However, no matter how much you may have paid for the image, you are unable to sell it on to a third-party (or parties), or to market it commercially as part of a logo, or advertising campaign, for instance.