Hermetic seal

When you close a jar of peanut butter, you twist on the lid until it snaps into place, right? Well, inside that lid, there's a little ring of rubber. When you screw the lid on, the rubber gets squished between the lid and the jar, making a super-tight seal. Nothing can get in or out of the jar through that seal - not air, not dirt, not even little ants. That's what we call a hermetic seal. It's a really strong, airtight seal that keeps things safe and protected. Just like your peanut butter!