Prepare your apples: Wash your apples thoroughly to remove any dirt or debris. Cut them into quarters, removing the cores and any damaged sections. Peeling is not necessary.
Cook. Place the apple quarters in a large pot and add just enough water to cover the bottom of the pot (about 1 inch deep) to prevent sticking. Cook over medium heat, stirring occasionally, until the apples are thoroughly soft and mushy, about 20-25 minutes.
Strain. Set a fine mesh strainer or cheesecloth over a large bowl or pot. Pour the cooked apples into the strainer and let the juice drain for at least 3 hours. For clearer juice, avoid pressing or squeezing the apples too hard; simply let the juice drip out. For even clearer juice, you may strain it a second time through a finer mesh or cheesecloth.
Fill jars. Use a canning funnel to pour the hot apple juice into the sterilized jars, leaving about ¼ inch of headspace. If desired, add ¼ teaspoon of citric acid or ascorbic acid to each quart jar to preserve color.
Rims and lids. Wipe the rims with a clean cloth. Place lids on top and screw rings on the fingertip tight.
Process. Place the filled jars in the water bath canner, making sure they are covered by at least 1-2 inches of water. Bring to a rolling boil and process the jars for 10 minutes (adjust processing time for elevations above 1,000 feet).
Cool. After processing, carefully remove the jars using a jar lifter and place them on a towel or cooling rack to cool for 12-24 hours. Check the seals before labeling and storing the jars in a cool, dark place.