(WHTM) — You have probably seen silica gel packets in many places such as shoeboxes, dried food, and even bubble wrap. It’s a white packet that always says ‘do not eat’ on it.

So what is silica gel and why is it in these places?

Silica gel packets are used to keep products at the correct humidity. These little packets take in moisture when there is too much of it in products or in the air. But, if the air gets too dry, they can re-release some of the water it has collected.

Silica gel, according to Discover Magazine, is categorized as a desiccant. Desiccants are used to create or sustain a state of dryness in its vicinity. These substances are used to keep goods dry in situations where excess moisture can either damage or lower the quality of the product they are placed in.

The packets work by having little pellets of water and silica, which happens to be the main component in sand. Science That Matters states that the little pellets have sponge-like structures. All the gaps between the molecules are what cause the gel to hold on to water so well.

If moist air comes in contact with the packet, the droplets will slowly build up and will eventually make contact with the pellets inside the packet. Once this happens the water will hold onto the silica gel tightly, while filing the internal structure of each pellet that is inside the packet.

Science That Matters stated that silica gel is nontoxic, but you should not even try to eat it as a snack. It may not get you sick but the Illinois Poison Control Center says that choking on the packet is its biggest risk. This is because people may think it is part of the food.

Since there can be confusion sometimes over what exactly is in the packet, it is recommended to call poison control if someone swallows a desiccant packet, just in case.