From a legal standpoint, it is important to use this particular mark or just make it clear who is the originator of a piece of art such as a photograph with a name etc. At the risk of biasing the answer, my feeling is that the mark is not worth the ink needed to print it, but I would be interested in people's opinions.
Actually if you created it, you own the copyright, and it isn't necessary to place that on the image. However, proving that it is your copyrighted work is another matter that makes the mark more important. For a while it was customary to write out "copyright", then the symbol if you prefer, your name, and the year. I also believe the date is quite important. I think the copyright symbol is OK, with your name, and year. In any case, I think publishing with these three items would go a long way in establishing ownership.
regards~Bill
I thought date was not important, especially if, you, as the originator of the work, are still alive.
What seems to be important these days and the threat of new laws is a way to clearly contact you, so a web site or email address. Otherwise "they" can try and claim it was orphaned.
(not being a lawyer, I would like clarification on what is necessary.)
It is not necessary to use the copyright symbol or provide any notice. Under the statute that was in effect prior to 1986, if you published a work without a copyright notice, then the work was consdered public domain.
Putting a copyright notice on a work does help to prove wilfull infringement if you sue someone for infringement. If you prove wilfull infringement, you may be entitled to increased damages in an infringement suit. Without the notice, a person could claim that there infringement was innocent and not wilful.
Of course, you need to actually register your copyright with the LIbrary of Congress to start a lawsuit in the US.
Copyrights are registered with the US Copyright Office. Here is a link to their FAQ. It has all the answers and links to the forms etc needed to copyright a work or body of work for legal protection. It's true that the work is copyrighted at the moment of creation, however only registration of the image affords the owner certain legal protection and remedies.