The "original" population of what is now Canada were the native tribes, in particular, the Algonquian, Cree, Huron, Ojibwe, and many others. Every subsequent migration of people can be categorized as immigrants. Over the last four hundred years, millions of immigrants from many regions of the world have emigrated to Canada.
Canada being a former colony of both Britain and France, its earliest significant immigration came from those two areas. The French began settling Canada in the late 16th and early 17th Centuies, as did the the British, more of whom migrated there from the 13 colonies following the American Revolution. Over the decades, Canada has seen significant immigration from all over the world, with sizable representation from China, India, Colombia, and Sri Lanka.
Canada's transition to independence from Great Britain was very gradual. The 1931 Statute of Westminister marked the formal separation of Canada from Great Britain, but it wasn't until the Canada Act of 1982 that it completed its separation from its former colonial master. Consequently, its immigration policy has not traversed a smooth chronological line.
The Immigration Act of 1910 formalized Canadian citizenship for British subjects already living there. In the modern era, the most significant developments in Canada's immigration policy were passage of the Immigration Act of 1976 and the Immigration and Refugee Protection Act of 2002. Recognizing the depth of differences between those supporting a more federalized system and those supporting more of a confederacy, the 1976 Act gave each individual province greater authority to determine its own immigration policies. That Act included provisions providing for greater exclusion of economic refugees who could be a drain on the country's social welfare system.
The Immigration and Refugee Protection Act of 2002 was an appendage of the 1976 Act, creating a more streamlined immigration process for foreign skilled workers who would contribute to the growth of Canada's economy and not represent a burden on the social welfare system. It is analogous to the H1B visa that the United States uses to admit skilled foreign workers who can help American high technology companies stay competitive.