What does the 'overflow' property control in CSS?

The 'overflow' property in CSS primarily determines how an element handles content that exceeds its box dimensions. When the content is too large to fit within the designated space of the element, the 'overflow' property specifies how that overflowing content should be treated. This can include options such as 'visible', allowing the extra content to spill out of the box, 'hidden', cutting off the extra content without providing access to it, 'scroll', adding scrollbars to enable viewing of the additional content, or 'auto', which only adds scrollbars if necessary.

By managing the visibility and interaction with overflowing content, the 'overflow' property plays a crucial role in layout design and usability, helping ensure that content is presented in a clear and organized manner even when it exceeds the typical boundaries of an element.