Hi there,
I am well aware of the term Copyright and almost everyone uses it in their respective website. i am a freelancer. does it serve any purpose if i display the copyright text in footer below? is it beneficial ? does the law protect our codes from being illegally duplicated just by displaying the text? and lastly apart from the copyright information what other information i should be displaying in the footer? is it professional if i use the link back to my portfolio website ?
Yes because if you don't put the copyright notice, any user may "think" that he can copy your content.
I don't think it will prevent you from enforcing him to delete the copied content, but I'm pretty sure it will reduce the number of people that copy it.
It depends on your country and I'm not a lawyer but in Canada and the US anything written by a person is the property of that person unless they say otherwise (or give up their right to an employer).
Google famously did not have a copyright notice during test but put one on so people would realize their simple page had loaded. People were waiting for the website to load because they were used to big pages with lots of content.
If you are making a site for a client you are paid for that service. I would only put a link back if your client says it's ok. Otherwise it's not tasteful.