Set 1 16-ounce mason jar or 2 8-ounce jars on a clean kitchen towel next to the stove, along with jar lids and a ladle.
In a saucepan over medium-high heat, combine cranberries, sugar, and lemon juice. Stir well and bring to a boil, stirring often to prevent sticking as the sugar melts and cranberries pop.
Once boiling, reduce heat to medium and continue to cook, stirring, for 8-10 minutes, until thickened and jammy. Do not overcook as the jam will continue to set as it cools.
Pour the jam into your jar(s), leaving ¼ inch of headspace. Use a wet towel to wipe the outside of the jar, then loosely place lid. Let cool to room temperature, then store in the refrigerator.
For canning
If processing in a water bath canner, prepare the canner by filling with water and heating to boiling before cooking the jam. Let the water simmer at a low boil while preparing the jam. Set aside two-piece jar lids.
Cook jam and fill jars as above, then place the lids and screw on bands just to fingertip tight. Carefully lower into water bath, place lid on the canning pot, and boil for 15 minutes.
Turn off heat, and let rest 5 minutes. Remove lid, and carefully remove jars, placing on a kitchen towel. Let rest undisturbed for 24 hours, then check for seal, label, and store in a cool, dry place.
Notes
Makes about 2 cups/16 ounces.
If your cranberries come in 12-ounce bags, you can use the whole bag! It will make a little extra jam. If desired, add 2 tablespoons more sugar with the additional fruit.