Copyright is different to copywriting which is the writing of ‘copy’, usually advertisements or press releases.
Copyright is the legal right to protect work you create and to control who can copy it. The digital age has made it easier than ever to copy material. But unless you created it, you don’t
own it. All work is copyrighted whether the © is included or not.
There are various tracking mechanisms available to authors for ensuring their work is not plagiarised, such as www.copyscape.com
For a brief overview of copyright, check out this page from Cleardocs.