Canada welcomes more than 35 million temporary residents each year. Unless they Canadian citizens or Canadian Permanent Residents, individuals coming to Canada for the purpose of visiting, studying or working may need a Temporary Resident Visa (TRV) from Citizenship and Immigration Canada (CIC) to enter Canada.
Some people are inadmissible–they are not allowed to come to Canada. Several things can make you inadmissible, including involvement in criminal activity, in human rights violations or in organized crime.
You can also be inadmissible for security, health or financial reasons.