“The [Canadian] Copyright Act is usually presented as a balance between promoting the public interest in the encouragement and the dissemination of works of the arts and intellect and obtaining a just reward for the creator.”
(Source: Théberge v Galerie d’Art du Petit Champlain Inc, 2002 SCC 34,  2 SCR 336, supra note 18 at para. 30)
Canadian copyright laws attempt to preserve this balance. On the one hand, authors should be compensated for the resources they use to create works: the promise of reward motivates creators and drives innovation. On the other hand, making works available to the general public allows others to use them to create new projects and serves the public interest.
The copyright paradox is that both paying creators and not paying them spurs innovation.
The concept of the public domain serves the public interest. When enough time has passed, works have generated most of the revenue they will earn—so the benefits to the public outweigh continued compensation for copyright holders. Does this seem unfair?
Canadian works enter the public domain 50 years after the author dies, and even later in the United States.
In some cases, works enter the public domain immediately, because they were not copyright-protected in the first place. For example, most documents published by the United States government are meant to serve the public interest, and you can use them freely. Canadian government documents are governed by a related but different concept called Crown copyright.
However, these are exceptions: in most cases, you should assume that recently published works are protected by copyright.
Many people assume that when authors make works freely available, they enter the public domain: anyone can copy, share, distribute, and adapt them without permission.
However, freely available works do not automatically enter the public domain. which is a complicated legal concept that differs from country to country.
Copyright protection has been automatic since 1928, when Canada signed the Berne Convention for the Protection of Literary and Artistic Works. You do not need to use the copyright symbol © or register your works for copyright protection, though there are advantages if you do. The United States signed the Convention in 1989.
This means that most works produced in North America today are automatically protected by copyright law, including online sources. Web creators can make their works freely available and give permission for others to share and adapt them, but they are still copyright holders. There are some tools available to assign works to the public domain, but you should generally assume that online works are copyright-protected—whether you see a copyright notice or not.
Please consult Creative Commons and Open Access for more information on freely available online works.