Component
also: components
A reusable piece of the screen, like a button, a menu or a product card. The frontend is built by combining many of them.
A self-contained, reusable unit of user interface, common in frameworks like React, Vue and SwiftUI. It combines layout, styling and behavior, can accept inputs (often called props), and can be nested inside other components.
Components are like Lego bricks. A product card is one brick; a product list is many cards snapped together. Change the brick's design once and every copy changes with it.
Agents build and fix screens component by component. Knowing that one component can appear on many pages helps you predict how far a change will spread.
I've pulled the star rating into its own component, so the product page and the reviews page now share the same code.
Make the booking button a reusable component and use it on both the class page and the teacher page.
Thinking a component is a whole page. Pages are usually made of many components, some as small as a single button.