On CIPO's web site, you may use the Canadian Patents Database to do your preliminary search of existing patents and have access to detailed descriptions and images of all patents issued in Canada since 1920. Patent applications published in Canada since 1989 may also be viewed.
The USPTO web site is much larger and has many more registrations than CIPO. Use the USPTO site as a starting point in your preliminary search of existing patents. You may also visit other country's IP offices, this is especially important if your invention or idea will have a presence in any nation.
Some helpful links: