What is the purpose of the 'clearfix' hack in CSS?

The 'clearfix' hack in CSS serves the purpose of containing floated elements within their parent container. When elements are floated, they are removed from the normal document flow, which can lead to issues where the parent container does not expand to encompass the floated children. This can result in layout problems, such as overlapping elements or a parent div collapsing to zero height.

The clearfix solution typically involves adding a specific CSS class that uses the ::after pseudo-element to generate a new block formatting context. By applying properties like content: ""; display: table; to the pseudo-element, the clearfix ensures that the parent container adjusts its height to include the floated elements. This technique effectively resolves the issue of layout collapse, maintaining the intended design and functionality of the webpage.

In contrast, styling elements with border effects, removing margins, or changing the display properties do not address the problem of containing floated elements, which is the primary goal of the clearfix method.