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Copyright
Copyright is a legal right created by the law of a country that grants the creator of an original work exclusive rights for its use and distribution.

Copyright is usually only for a limited time. The exclusive rights are not absolute but limited by limitations and exceptions to Copyright law, including fair use.

Copyright are a form of Intellectual Property Rights.

A major limitation on copyright is that Copyright protects only the original expression of ideas, and not the underlying ideas themselves.

The general rule is that the year to include in a copyright notice is the year of first publication of the work. First publication is when the work is made available to the public without restriction. This includes selling a book or leaving free copies of it in a public place or posting content on your blog. Publication does not include, for example, circulating copies internally to co-workers.

For compilations or derivative works which incorporate previously published content, use the year of first publication of the compilation or derivative work.

New versions or editions of works should contain the publication date of the new version or edition. For constantly evolving websites and blogs that contain works published over several years, the notice may include a range of years (e.g., 2009–2018), starting from the date of the oldest published elements and ending with the date of the newest published elements.

Copyright notice is not mandatory in most countries. It is not mandatory in the United States or in Canada. Specifically, Copyright is not required in Berne Copyright Treaty countries. In these countries, use of the Copyright notice and symbol is still useful and is a good idea. In these situations, the purpose of the Copyright notice is to educate others or to remind others that Copyright exists in your work and to respect that Copyright.

Some mistakenly think that the lack of a Copyright notice means that the work is in the Public Domain or free to use without obtaining permission from the Copyright holder.

There might be more information for this subject on one of the following: