Citizens of some countries are exempt from this requirement but most are not. These visas may be single or multiple-entry, and typically allow a visitor to enter and remain in Canada for up to 6 months at a time.
Generally speaking, when assessing an application for a Temporary Resident Visa, the immigration authorities will consider the purpose of the visit, whether the applicant has sufficient funds to support themselves during their stay, and whether the applicant is likely to return to their home country at the end of their visit.
If the visa applicant has a good reason for wanting to come to Canada and otherwise meets the relevant criteria, then they will likely be approved. However, the approval of this type of visa application is highly discretionary on the part of the visa officer, so a properly prepared application is essential for success.
Most applications for Temporary Resident Visas (TRV’s) are by those who wish to visit Canada for tourism or some temporary personal reason other than for work or business. If the foreign applicant will be visiting some specific person in Canada, then it is helpful to obtain an invitation letter from that person for use in the application. Proof of funds will also be required, and return tickets are helpful to demonstrate an intention to return to the home country at the end of the visit.