It is a way of thinking before it is paperwork. You describe the product and its process step by step, ask what could go wrong at each step — biological, chemical, physical — and decide which steps actually control the risk. Each of those gets a limit you can measure, a check that proves you hit it, and a defined response for when you do not.
In practice HACCP is a document plus the records that show you followed it: cook and cooling temperatures, receiving checks, sanitation logs, batch codes. That evidence trail is the part buyers care about. Retailers, distributors and institutional buyers often ask for a HACCP-based plan as a condition of supply, whether or not anyone else asks you for one.
Whether a written plan is required of your business depends on what you make and where you sell it; settle that with the authority that issues your permit. As a starting point, the Canadian Food Inspection Agency states you do not need a Safe Food for Canadians licence to trade food within your province or to prepare food that will be sold or consumed in your province — import, export and interprovincial shipping are what change the answer.
If you work in a shared kitchen, your plan has to account for a room you do not control: how your ingredients are segregated in shared storage, how allergens are handled between tenants, and what you verify about the state of the space before you start. Those are your control points even though the equipment is not yours. Kitchen listings describe storage and cleaning terms.