As discussed below, public domain isn't a concept in many legislations (copyright vs. authors' right e.g. – you can relinquish your exclusive right to copy, but

As discussed below, public domain isn't a concept in many legislations (copyright vs. authors' right e.g. – you can relinquish your exclusive right to copy, but not your authorship), so minimal licenses like CC0 are needed to really put your works under public-domain-or-equivalent worldwide.