In my position with Gnarlybooks I tend to have a lot of contact with business owners of all types and businesses. This can lead to some interesting conversation as you can probably imagine. Some of the more interesting ones I have had are with self-employed people that don't really have a 'business' in the traditional sense.
It's a Gig
The gig economy has been growing significantly with the introduction of apps like Uber, Fiverr etc. People can earn money supplementing their regular source of income or work a gig as almost at a 'full-time' type of scenario. A gig can be a temporary employment contract (you are paid as am employee with statutory deductions subtracted).
However from a taxation perspective, if you do not have an employment contract for your gig then it is considered to be self-employed income which you will need to report and yes pay taxes on. You may even have to register to collect Sales Tax (HST/GST/PST) in Canada.
But is it a Business?
From strictly technical side it is a business and you are the proprietor. You are operating (probably) under your own name as a Sole Proprietor and would be considered at least in some part self employed.
However, the difference between a gig and a business is really the outlook of the proprietor. If you are just making some extra income on the side the chances are good your gig isn't something you are looking to grow into. It just is what it is: a gig, and it is serving it's purpose of providing you with a bit of extra income whether that is to boost your savings, pay off some debt, or enjoy some mai tais on a beach somewhere.
If your gig is something you are looking at with a long term perspective it is probably more of a business. Either way you will have to report the income you earn.