What is a "status" in Canada?
If you are a visitor to Canada and you had a Temporary Resident Visa (TRV), Super Visa, or you study or work in Canada, you are allowed to stay in Canada until a specific day.
This day may be mentioned on your study / work authorization. You may calculate this day by yourself if you are a visitor and you know you cannot stay for more than six months. Or this day may be noted in your passport by a Canadian Border Service Agency (CBSA) official when you come to Canada.
Every temporary resident must carefully monitor their status and know when it expires. When you lose your status, you are in Canada illegally and may be deported and banned from further travel to Canada.
Canadian immigration officials understand that sometimes people may forget to extend (or change) their status. For this reason, they give a 90 days grace period to allow people to apply to restore their status.
In 2020, as a temporary COVID-19 measure, applicants are allowed to restore their status until the end of 2020 if their status expired after January 30, 2020.