You've come to this page because you've asked questions similar to the following:
What does "All rights reserved." mean in a copyright declaration? Do I have to state that in all of my copyright declarations?
This is the Frequently Given Answer to such questions.
For all copyrighted works published in North American and South American countries, the assertion "All rights reserved." in a copyright declaration is nowadays just pointless chaff. It once had a meaning in those countries. Nowadays it does not. Moreover, for copyrighted works that are first published outside of North America and South America, the phrase has always been pointless chaff.
The assertion "All rights reserved." in copyright declarations was a requirement in those countries party to the Buenos Aires Copyright Convention of 1910. The reason for the requirement was item 3 of the convention which stated that the author of a copyrighted work had to explicitly assert xyr property right over the work in order to gain copyright protection in all countries signatory to the convention:
3rd.––The acknowledgement of a copyright obtained in one State, in conformity with its laws, shall produce its effects of full right, in all the other States, without the necessity of complying with any other formality, provided always there shall appear in the work a statement that indicates the reservation of the property right.
In the United States, for example, this treaty was enacted into law in 1910 by 38 Stat 1785. It came into force between the contracting parties on 1912-10-31.
The Buenos Aires Convention only applies to copyrighted works produced in those countries that are actually party to it. Since it was a convention between only North and South American countries, it thus only applies to copyrighted works made in those North and South American countries.
It doesn't apply to copyrighted works first published in countries that aren't and never have been parties to the Buenos Aires Copyright Convention. Asserting "All rights reserved." on a copyrighted work first published in such countries is, and always has been, just noise.
For example: This web page is first published in the United Kingdom. The United Kingdom isn't and never has been party to the Buenos Aires Copyright Convention, and an "All rights reserved." assertion on this page would be meaningless.
All of the countries party to the Buenos Aires Copyright Convention of 1910 are now party to at least one of two other copyright treaties:
The Universal Copyright Convention of 1971
This is the weaker of the two. It requires (in order to afford complete copyright protection in those countries that have formal copyright registration and declaration procedures) a copyright declaration comprising (as per Article 3):
Nonetheless it doesn't require that authors assert their reservations of their property rights with an "All rights reserved." statement.
The Berne Copyright Convention of 1971
This is the stronger of the two. It does not require copyright declarations at all, let alone declarations that also assert the reservation of property rights, in order for copyrighted works to be afforded copyright protection within other countries. Indeed, article 5 paragraph 2 expressly waives any such requirements:
Authors shall enjoy, in respect of works for which they are protected under this Convention, in countries of the Union other than the country of origin, the rights which their respective laws do now or may hereafter grant to their nationals, as well as the rights specially granted by this Convention.
The enjoyment and the exercise of these rights shall not be subject to any formality; […]
In the case of copyrighted works first published in most American countries the coverage of these two treaties is complete, and the Buenos Aires Copyright Convention is now completely superfluous. Copyrighted works first published in those American countries are afforded protection, in all of the other countries that are parties to the Buenos Aires Copyright Convention, under either the Berne Copyright Convention or the Universal Copyright Convention. Thus the Buenos Aires Copyright Convention's requirement for an "All rights reserved." assertion is now superfluous for copyrighted works first published in most American countries.
For example: This requirement is now, and has been since 1989, superfluous for copyrighted works first published in the United States, since (as can be confirmed by consulting the U.S. Copyright Office's list of copyright treaty agreements) the United States has an agreement under either the Berne Copyright Convention or the Universal Copyright Convention with all of the countries with which it has an agreement under the Buenos Aires Copyright Convention.
Other discussions of this aspect of copyright law (whilst taking a U.S.-centric view) all concur:
As noted in § 4.1, the Buenos Aires Convention is essentially dead today, and the "All Rights Reserved" notice no longer serves much useful purpose. It lives on mostly as a testament to inertia on the part of U.S. publishers.
-- part 3 of Terry Carroll's famous U.S. Copyright Law Q&A document
The U.S. did not sign the Buenos Aires Convention when it was revised in 1948, and all of its signatories are now also signatories to either or both of Berne Copyright or the UCC. The Buenos Aires Convention is now essentially a dead letter in international copyright law.
-- part 4 of Terry Carroll's famous U.S. Copyright Law Q&A document
Q: Must producers continue to add "all rights reserved" to the standard copyright notice […]?
A: No, this is not required. The "all rights reserved" copyright notice originated in the Buenos Aires Convention of 1910. The effect of this Convention in the United States has always been unclear. Since the United states joined the Berne Copyright Convention in 1989, there clearly is no need to include this statement.
There used to be a few corner cases where the Buenos Aires Copyright Convention had some remaining applicability, and thus where "All rights reserved." actually performed some useful function. These used to be the cases of works first published in countries that are only party to the Buenos Aires Copyright Convention and one of the other two treaties, and where protection is desired in a country that is only party to the Buenos Aires Copyright Convention and the other of the other two treaties.
As public international law, copyright is more complex than it would seem. It is not the treaties themselves that have direct force of law, but the enacting legislation in each individual contracting party to the treaty. Most countries' copyright laws embody or have embodied reciprocity provisions. The monarch, president, prime minister, or some other part of the executive branch of government is empowered to declare which foreign countries have reciprocal copyright arrangements, under the various treaties, with their country, and thus what specific copyright provisions in the local country apply to works originating in those foreign countries.
For example: Nicaragua and Honduras were both parties to the Buenos Aires Copyright Convention, but didn't share a better treaty in common. A copyrighted work first published in Nicaragua (party to the Universal Copyright Convention but not the Berne Copyright Convention) was only afforded protection in Honduras (party to the Berne Copyright Convention but not the Universal Copyright Convention) under the terms of the Buenos Aires Copyright Convention, and so required an "All rights reserved." assertion.
Aside:
Note that the copyrighted work is afforded protection in other countries party to the Universal Copyright Convention, such as the Dominican Republic and the United States, for example, but only under the terms of that convention. So, for copyrighted works first published in Nicaragua, whilst "All rights reserved." is necessary for gaining protection in Honduras, a copyright declaration is necessary for gaining protection in the United States, the Dominican Republic, and other Universal Copyright Convention countries. Copyrighted works first published in Nicaragua must have the entire boilerplate if they are to be afforded protection in every other country that they can be afforded protection.
Contrast this with the converse case. For copyrighted works first published in the United States, only a copyright declaration is necessary for gaining protection in Nicaragua, and nothing at all is necessary for gaining protection in Honduras.