It is not necessary to register a trademark in order to have valid trademark rights. Such rights derive from the old English Common Law, and hence the mark is often called a common-law or unregistered trademark. As soon as a valid trademark has been properly used, these common-law trademark rights arise, but they are very weak rights. If your common-law trademark is infringed, then you can sue in the Courts, but your rights are difficult to prove and enforce. You must prove that there is “good will” associated with your mark. Also, these rights only extend as far as your reputation extends and no further.
Registering your trademark provides you with much stronger protections. The Trademarks Act sets up an official Registry of Trademarks and everyone is deemed to be aware of what is on this Registry. As a result, if someone uses your registered trademark even if they don’t actually know about it, they are nevertheless infringing and you can sue them. Your rights are also good throughout Canada.