Semantic zoom is a touch-optimized technique used by Windows Store apps in Windows 8.1 for presenting and navigating large sets of related data or content within a single view (such as a photo album, app list, or address book).
While navigating content is possible through panning and scrolling alone, powerful navigational and organizational capabilities are possible when paired with semantic zoom.
Panning and scrolling are useful for small sets of content and short distances. However, navigation quickly becomes cumbersome for large sets of content. Semantic zoom greatly reduces the perception of traveling long distances when navigating through large amounts of content and provides quick and easy access to locations within the content.