One of the main objectives of Immigration, Refugees and Citizenship Canada (IRCC) is family reunification. However, not all family members are eligible for sponsorship under the Family Class, and there are very strict rules and regulations that apply to the sponsor as well as the family members being sponsored.
The most common Family Class applications are for sponsorship of a spouse, common-law partner, or dependent children.
It is also possible to sponsor parents and grandparents for permanent residence in Canada, although the financial requirements are greater and there is an annual cap of 10,000 applications for parents and grandparents, and the selection process is now lottery-based.
In some very special situations, it is possible to sponsor another relative. Please see: http://www.cic.gc.ca/english/immigrate/sponsor/relatives-apply-who.asp