Onions typically have 10 to 15 layers. However, the exact number of layers can vary depending on the type of onion and its size. Common onions, like yellow onions, usually have more layers, while sweet onions may have fewer.
The layers of an onion are actually modified leaves that keep the bulb healthy and store energy for the plant. Each layer surrounds the core of the onion and can be peeled away. When you cut into an onion, you can see the layered structure, which is not only interesting but also plays a role in how the onion cooks and flavors dishes.