A container is a designated area or element that holds and organizes other UI elements, content, or components within a defined space. Containers play a crucial role in structuring and arranging elements on a webpage or within an application. They help create visual order, establish grouping, and manage the layout of content.

Containers can have their own styling, background, and spacing properties, allowing designers to create distinct visual areas within a user interface. They can also be more or less invisible and only provide structure or balance behind the scenes in the interface’s code.