Actually, it is technically free.
Any creative work is copyright the minute it comes into being. The trick is, if you register your (c) you face a much shorter legal process.
TMa really have to be registered to be recognized by the court (see the Air Jordan case; a guy had made these shoes by this name ages before Nike, and if he had registered, he would have been entitled to damages; but he didn't and the case was dismissed).
Basically, a copyright suit goes like this (this is very simplified):
1. Both parties file papers.
2. The respondent/defendent has so much time to answer for the damages.
If possible, they will try prove nothing actionable occurred.
For example, let's say I copied three pages of an academic book and gave it my class. This falls under the education stipulation of fair use of copyright, and therefore is not actionable.
The flip side is, if I copied 2/3 of the book, it's actionable. This gets hairy around 30 pages, and these sorts of suits are very common over college texts.
3. An initial hearing decides whether both parties have standing.
In other words, I cannot sue you for infringing DarkBASIC's copyright, even if you did; DB has to do that themselves... therefore, I do not have standing and the case is dismissed.
This phase is where your registration really counts. If either one of you has a copyright, there will probably be standing.
4. Both sides hand over info.
5. A determination is made whther infringement occurred.
If you have registered, the defendent has to pay up a fixed amount per infraction (it's BIG, usually over $10,000).
If not, then another phase commences where you must determine the value of the copyright, then damaages will be assigned.
This is tricky, and hands an appeal to the defendent, since that sort of determination is always suspect.
6. With damages determined, a determination is made whether the infringement was overt, intentional. At this point, punitive damages can be assigned.
However, this phase is usually skipped by the plaintiff, simply because it, again, increases the chance of a successful appeal.
This is atypical.
Really, to get to this phase, you have to have committed criminal fraud, in which case you face something a lot worse than a civil proceeding.
We can't stop here! This is bat country!