Rinse the cranberries in cold water, removing any bruised or damaged ones.
In a saucepan, combine cranberries, sugar, water, orange zest, orange juice, and the optional cinnamon stick.
Bring the mixture to a boil over medium-high heat. Reduce heat to low and let it simmer for 10-12 minutes. You'll hear cranberries pop - that's okay!
Stir occasionally and gently mash some cranberries with the back of a wooden spoon for texture.
Taste the sauce and adjust sweetness by adding more sugar if needed.
Remove from heat and allow the sauce to cool; it will thicken as it cools.
Transfer the homemade cranberry sauce to a serving dish, removing the cinnamon stick (if used), and serve.