If you’re new to cooking, terms like zest and pith might be unfamiliar to you. They refer to parts of a citrus peel.

The zest is the thin, colorful outer layer of the peel. Full of aromatic oils, it packs loads of flavor. In the case of sour citrus, like lemons and limes, the zest provides a nonacidic version of the fruit’s flavor, useful for baked goods and other instances where sourness isn’t wanted.

The pith is the thicker, spongy white layer. It’s very bitter, which is why recipes often suggest avoiding as much of it as possible when removing the zest. Our Candied Citrus Peel recipe is an exception—in this case, the bitterness of the pith is a welcome counterbalance to the high amount of sugar in the recipe.

If you’re a fan of citrus, check out more citrus recipes.