Copyright exists as soon as you create a ‘document’ (read any sort of work including computer programs) and doesn’t require you to act in any way to “copyright it” as you suggest. There is no registration process and using the (c) mark only provides a clearer indication that it is indeed copyright.

There is no registry of copyright documents and the process is that should the author of that document suspect that someone has breached the copyright of his or her document, then it is up to the author to pursue it under the copyright law of the country. The author can simply ask the offended to cease and desist and if they don’t then take legal action.

The onus is on the author or owner of the document – note that copyright can transfer to another party and although may initially vest in the author, it may be purchased from the author or indeed the contract for the creation of the document may determine the owner is the client of the autohr from the beginning.

Patent is another story and as you suggest is a process of verification and registration of the item, not necessarily a document (in the broadest sense) at all.