Prepare your jars: Start by sterilizing your jars and rings, either by running them through the dishwasher on a hot cycle or by boiling them in water. Be sure to use new, unused lids to ensure a good seal.
Prepare the water bath: Fill your water bath canner with enough water to cover the jars by at least 2 inches. Bring the water to a boil and keep it warm until you are ready to process the jars.
Peel and cut the peaches: To make peeling the peaches easier, you can blanch them by immersing them in boiling water for 30-60 seconds and then immediately placing them in an ice water bath. The peels should peel off easily. Pro tip: I like to use both sides of my sink for this process: one side for draining the blanched peaches and the other side filled with ice-cold water. After blanching, I lift the entire colander of peaches from one side of the sink and place it directly into the ice water on the other side. This method is much easier than scooping out individual peaches and makes peeling them a breeze. Once peeled, slice the peaches and place them in the jars.
Add the syrup: Prepare your syrup by dissolving 2 cups of sugar in 6 cups of hot water. Pour the hot syrup over the peaches in each jar, leaving about 1/2 inch of head space. Gently tap the jars on the counter to remove any air bubbles and wipe the rims before sealing with the lids and rings.
Process the jars: Carefully place the jars into the water bath canner. Bring the water to a boil and process the jars for 25 minutes (adjust the processing time if you are at a high altitude).
Cool and store: After processing, turn off the heat and let the jars sit in the canning container for 5 minutes. Then use tongs or a jar lifter to transfer the jars to a towel-lined countertop. Allow the jars to cool completely before storing in a cool, dark place.