Watermarks help send all sorts of people to my website. Very small in lower right.
I know that Facebook takes it off when showing the people the center portion of the image (this is done automatically, not by people, by the way), but it shows up in the full image.
All sorts of people find my website, and I let my 720 pixel watermarked images go freely around the internet. It is like water down the river. It goes to the ocean, and then comes back to me again.
In fact, maybe there is a reason why it is called a watermark even though there is no water involved with the digital type of watermark. It's because it truly is like water going to the ocean and then coming back again to me!
This is probably the most intelligent use of watermarks I have every heard of. I may have to reconsider my opinion of them.
Perhaps I should have said signature, instead of watermark, although they are pretty similar in a lot of ways when applied visibly to a photograph.
For me, it's mostly in an effort to let people know who took the photo to more easily look me up, as well as a token effort in case someone does
take my image and use it (on the web, I only put up smaller sizes) commercially or otherwise. That way, if they remove it, it's definitely willful infringement. After all, they had to make an effort to remove it, not "oops, didn't know". More of a trip-wire, than real protection.