ItemList (schema.org)
ItemList is a schema.org data type for marking up ordered or unordered lists, such as rankings, playlists or product categories. The itemListElement property, with individual ListItem entries and their position, makes the order of the list items machine-readable; itemListOrder and numberOfItems are also available.
In practice
Google uses ItemList above all as the basis for carousel rich results, in which several items, recipes, courses or restaurants for instance, appear as a horizontally scrollable row of tiles directly in the search results. Important: purely navigational or internal link lists without editorial value do not automatically trigger a rich result, and Google still assesses the content quality and reach of the underlying pages. Depending on the content type, additional requirements apply, such as those for Recipe or Course markup. The numberOfItems and itemListOrder properties also help with paginated or sorted lists that span several pages.