Prepare your jars and/or freezer containers: wash well and pour boiling water into jars and let them sit while making the jam.
Prepare your fruit: hull strawberries and partially run through a food processor to make the crushing go quicker; other berries can just be crushed with a potato masher, a couple cups at a time. Other fruit like peaches and nectarines will need to be chopped finely.
Make the jam: Add sugar and pectin to a large bowl and stir together well. Add your prepared fruit and stir for 3 minutes.
Pour the jam into clean jars, leaving 1/2 to 1 inch headspace (for freezer expansion); place lids on jars and let the jars sit undisturbed for 30 minutes.
Refrigerate what you want to eat now (they will keep for about 3 weeks) and freeze the rest for up to a year. Be sure to label and date all the containers before freezing.
Notes
*If using a different pectin, follow those directions.