The down payment is the first chunk of change you'll put toward a new home. The rest of the cost of the house will be covered by a mortgage loan that you'll chip away at over time, but the down payment is your way of telling lenders "Yes, I can afford this house, and I'll prove it by putting this money on the table right from the get-go."
How much your down payment will cost you depends on the price of the home. The government of Canada says that, for homes that cost less than $500,000, the minimum down payment is 5 percent of the purchase price. For homes between $500,000 and $999,999, you'll pay at least 5 percent of the first $500,000 of the purchase price, then 10 percent of however much of the cost is left. If you buy a house that costs $1 million or more, you'll pay a full 20 percent down. If mental math isn't your strong suit, don't worry. There are calculators that will do the work for you.
Keep in mind that no matter what the home you want to buy is listed at, if you have less than 20% for a down payment, you'll have to pay for mortgage insurance, which protects your lender in case you can't pay back your loan. That all adds up to more money out of your pocket, but if getting an insured mortgage is absolutely necessary, and you can manage the higher mortgage payments, you shouldn't let that stop you from buying your home.
On the flip side, paying more upfront could help you have less debt, setting you up to pay off your mortgage sooner rather than later.