But lo and behold! These numbers are anything but random. As an illuminating Quora user revealed, the numbers in these triangles mark the kind of uses the plastic is safe for.

Here’s the exact breakdown of what each number signifies, and just why you need to be aware of it for the safety of yourself and your loved ones.

1. If the triangle has the number ‘1’ inside it, the plastic used to manufacture that bottle is made of Polyethylene Terephthalate (PET).

Commonly used for bottled water or soft drinks, it’s safe for a single use and should never be heated. This kind of plastic degenerates into its contents over time. So be sure  that you do not use it past its expiry date. Hence the message that reads ‘Crush The Bottle After Use’.

2. If the triangle has the number ‘2’ in it, it indicates that the bottle or container is made of high-density Polyethylene.

This plastic is often used for detergent and shampoo containers among other common items.

3. The number ‘3’ inside the triangle should alert you not to use that plastic. They are made of Polyvinyl Chloride (PVC) and contain carcinogens.

Among the few items this category of plastic is found in, are peanut butter jars.

4. The plastics that have the number ‘4’ inside the triangle are reusable all the way.

This is the variety of plastic that reusable shopping bags are usually made of.

5. The safest of all plastics will have the number ‘5’ inside the triangle.

It’s rather commonly found in ice-cream cups, drinking straws and syrup bottles and other containers for medicine or food.

6. The numbers ‘6’ and ‘7’ should serve as big red flags as the plastics marked with these numbers are highly dangerous.

They contain Polystyrene and Polycarbonate Bisphenol A (BPA) respectively and act as serious hormone disruptors in the human body. Continued use of such plastics can lead to cancer and heart disease.

They’re commonly used to manufacture plastic spoons, plastic forks, water bottles etc. At times, Tupperware containers have been marked with the number ‘7’. Now while Tupperware containers are considered food safe for the most part, they are  manufactured with BPA and this can prove harmful in the long run. So watch out!

7. Another symbol you might find your plastic containers marked with is a wine glass and fork. This is an international sign for ‘party safe’ plastic.

It basically indicates that this variety is safe for food contact.

This is important information, y’all. And as the wise Quora user said, “Now it’s your turn to educate other people.”