There are three kinds of temporary residence in Canada. They are visitor visas, study permits and work permits. In order to come to Canada, or stay in Canada, through any of these forms of residence, you need to make an application.
A visitor visa is an application to come to Canada for a temporary stay of six months in for tourism, to visit family or friends or possibly to complete a very short (less than six month) course. It could be for a combination of reasons. Some countries are called "visa exempt". These are countries from which you do you need to apply for a visa, but something called an Electronic Travel Authorization (ETA) if you are travelling by air, but you will not need it if you are travelling by boat, bus or car.
The requirements for a visa are often different for different countries or origin. What you need to do basically depends on where you are travelling from. There may be a requirement for something called a "letter of invitation", which is written bey the person or institution you will be visiting. General requirements include proving that you are going to only stay in Canada temporarily. This means proving that you have an established life in your country of origin to which you will return (job, family, etc) and that you have money to support yourself for your trip. For many, visitor's visas are very straightforward, but for others, there many be some hurdles, such as if you will have someone else provide your financial support while travelling. There may be other complications, such as if you have a previous travel history in Canada that includes overstaying.
While in Canada on a visitor's visa, you cannot legally work in Canada
To come to Canada on a study permit, you first need to gain admission to a designated learning institution. It is important to ensure that you have proof of admission to a school on the list in order to be eligible for a study permit. you also need proof that you can support yourself and any dependent children who will be coming with you to Canada. Depending on the country that you are coming from, you may also need to do a medical exam.
Your study permit will have conditions. A typical study permit allows you to work part time on campus. There may be some variations to what is allowed for work. It is important to follow the obligations in your permit. Any work done outside of what is allowed will be considered a violation of the study permit. Study permits have limited allowance for work. To be able to work full time in Canada, a work permit is required.
You should also be aware that international students in Canada will pay considerably more for tuition than Canadian Citizens or permanent residents, which are called differential fees. If finances are an issue, you may want to give careful consideration to what schools that have your program of interest offer exemptions or more favourable fees. Educational institutions and provincial governments have control over the fees.
Work permits are required to come to Canada to be a temporary worker. There are a number of programs in Canada that manage temporary work for foreign workers. I will be updating this page for more information, but for now I will keep it simple. There are programs for those who are already in Canada with Canadian experience and then there are programs for those outside of Canada. For those outside Canada, the tow major groups and agricultural workers and everyone else. Agricultural workers can only be from participating countries.
If you are applying from outside of Canada, you will need to have a job offer before you apply. Finding work will involve finding employers that have something called a Labour Market Impact Assessment (LMIA). Employers need to apply for these to get permission from the Canadian government to hire foreign workers. There are many employers who post jobs saying that they have an "LMIA" or that say they will work with you or your agent to obtain an LMIA. Many applicants decide to go through recruiters to get Canadian jobs. However, be cautious, as many recruiters charge very high fees.
Once you have your job offer, you will need to follow the instructions for work permits that apply to your country of origin. Work permit applications can involve a number of steps and may be difficult for many.