A trademark is literally a mark that one business uses to distinguish its products or services from another. This trademark definition from the Intellectual Property Institute of Canada (IPIC) is more detailed:
A trade-mark is a word, design, number, two-dimensional or three-dimensional form, sound or color, or a combination of two or more of these elements which a trader uses to distinguish his/her products or services from those of his/her competitors and serves to establish goodwill with the consumer.
A trademark is not a trade name. A trade name is the name under which you conduct your business. It can only be registered under the Trade-Marks Act if it is used to identify wares or services.
As businesses primarily use trademarks for marketing purposes, most businesses register their trademark(s) so other businesses cant use them. In Canada, trademark registration gives the registered owner of the trademark the exclusive right to use the trademark throughout Canada, and the right to sue for infringement of the registered trademark.
The first step to trademark registration is to search to see if any other business has registered or applied to register a similar trademark. The Canadian Intellectual Property Office has an online Canadian Trademarks Database that you can use. You may wish to use a registered trademark agent to help you through the application process.
For more about trademarks and trademark registration, see Trademark Registration in Canada.

