1. Jars are ancient history. The oldest glass jars were made in ancient Egypt and Mesopotamia over 3,500 years ago! People shaped melted glass around sand cores to hold precious oils and perfumes.

2. Mason jars were invented by a tinsmith. In 1858, a man named John Landis Mason invented the screw-on metal lid. Before his invention, people sealed jars with messy wax or corks that often leaked!

3. Glass jars are made of super-heated sand. To make a glass jar, factory machines heat sand, soda ash, and limestone to a scorching 2,800°F (1,500°C) until it melts into liquid, then blow air into it like a balloon to form the jar shape.

4. They are endlessly recyclable. Glass jars can be melted down and remade into brand-new jars over and over again forever without losing strength or quality!

5. Napoleon helped invent canned food jars. French leader Napoleon Bonaparte offered a massive reward to anyone who could figure out how to keep food fresh for his army. A chef named Nicolas Appert won by boiling food inside sealed glass jars!

6. Jars create their own vacuum seals. When hot food or liquid cools down inside a jar with a proper lid, the air inside shrinks. This pulls the lid down with a satisfying "pop!" sound, locking out air and germs.

7. Old glass jars were often blue or green. Antique jars from the 1800s were usually aqua-colored because the sand used to make them had natural iron impurities inside.