Put three pint jars or six half pints (or some combintion thereof) in your canning pot and bring to a boil.
Combine fruit and sugar in a heavy, non-reactive pot. Bring to a boil and let bubble for a good twenty minutes, occasionally skimming the foam from the surface of the fruit as it develops. Add the pectin and boil for another five minutes. You want to cook it until it looks like boiling sugar - thick and viscous.
Kill the heat, fill your jars, wipe rims, apply the lids and rings and process in the hot water bath for 10 minutes. Remove jars from water and let cool on the countertop. When the jars are cool (I typically wait until overnight), remove the rings and test the seal by picking the jar up by the lid. If it stays put, your jars are good to store indefinitely.
I love the flavor of sour cherries, so I didn't add a drop of extra flavor to this jam. However, you are welcome to spice things up with cinnamon, nutmeg, cardamom, vanilla or orange (or anything else).