We need to have sufficient quantities of calcium on a regular basis because it is a mineral that builds up our bones. If you want to have strong bones, have calcium. The best source of calcium is of course milk and milk products. But many of us are lactose intolerant or on a vegan diet and both these situations do not allow us to have milk and milk products. But you need not lose out on your calcium intake even then as you can have these foods that are rich sources of calcium. Find the list in the link shared below. You may ignore the non-vegetarian sources of calcium suggested if you are a vegan.