Most fruit preserves and pickles are sufficiently high in acid to be canned via a method called water bath canning, where jars are submerged in boiling water for a prescribed amount of time. This destroys any pathogens in the food, and creates a seal, thereby rendering the jars shelf-stable.
Canning has been around for 200 years, but I was new to the practice. What did I learn? It's pretty easy, definitely fun and a wonderful way to preserve fruits and veggies so I can enjoy them long past their growing season.