Components are useful for anything that you want to add as part of a whole. Fabric is a great example for sofas, or light bulbs when purchasing a pendant light and the bulbs are extra. Many of our users like to use it to show association, so they can generate an export showing that the components are part of the main item.
Here's a quick video on how to create components:
Easy, right? π
*Note: If you add pricing for a component, it will also add it to the pricing calculator, which means the component price will be multiplied by the main item qty and the same markup % will be applied (see example below).