Cardboard is probably one of the easiest things to recycle. There’s no need to check numbers. There’s no rinsing. There are no caps. So it’s no surprise we recycle about 77 percent of all cardboard that is recyclable. Did you know not all cardboard is recyclable?

There are two kinds of cardboard: corrugated cardboard, which has a wavy inner layer and is used to make brown packing boxes, and paperboard, which is a single layer of gray cardboard that’s used in making cereal boxes and other packages. Both are recyclable—as long as they don’t fall into these categories:

• Cardboard contaminated with grease—like a pizza box

• Cardboard coated with wax or resin, which is done to help strengthen it when wet—like juice boxes and milk cartons

• Cardboard that’s wet—because it will clog automated sorting machines

Here’s a trick for pizza boxes: You can pull the top off of your pizza box and recycle the clean top and throw away the greasy bottom.

What about tape? If you’re recycling shipping boxes or other boxes with tape or labels, you can leave those on when recycling the box.

Finally, it’s helpful to break down boxes before recycling them, because they’re easier to process when they’re fully flattened. And they’ll take up less space in your recycling bin, too.